The vacationing couple from Hattingen, Germany, showed up at Michael Naess’s shipshape Queens apartment at the end of February. They had never met before. Nonetheless, here they were, digging into scrambled eggs, sipping coffee and chatting companionably with him on a Saturday morning. A German radio station, plucked from the Internet, rendered a flavor of home.  The couple consisted of Dark Bontkowski, 52, a test driver for a German shock absorber maker, and his girlfriend, Martina Held, 48, a graphic designer for a financial newspaper. Mr. Bontkowski mentioned that, implausibly, he is a test driver who owns no car of his own. It was a needed expense reduction after he got divorced. He pedals to work on a bicycle, 22 miles each way.  The couple was occupying Mr. Naess’s spare bedroom for 10 days.  Awkward, but not really awkward. They were paying guests.  Over the past 10 months, Mr. Naess has had a parade of 72 strangers living with him, respondents to his overture of: “Beautiful room for rent in Astoria” on the website Airbnb. They have drunk his beer and indulged in his muffins and dirtied his guest towels. They have come from Italy, Canada, India, South Korea, Belgium, France, New Zealand, the Czech Republic, Bulgaria and so on and so forth. Among the so forth are the domestic bookings: Austin, Tex.; Waterloo, Calif.; and Washington, D.C. Members of this international bazaar, usually in pairs, have stayed from two nights to a month. Mr. Naess may bump into them in the mornings; then they might intersect in the evenings, decompressing together in the living room. For the most part, they glide past one another.  This is life as a hyperactive New York City “host” in that swelling substratum of the hospitality industry that unfolds in people’s homes, all part of the modern world’s sharing economy, spinning by with serial comings and goings.  Some things to know about Mr. Naess. He is 37, Texas-born, tall and lean, a sunny, genial man with an endlessly repeating smile. He is one of close to 350,000 hosts worldwide on Airbnb, the short-term home rental company that matches those with rooms to let and those who want to rent them in 35,000 cities. In New York, Mr. Naess is among 15,000 hosts listed on Airbnb, and easily among the busiest individual ones.  Some things to know about hosts. By and large, they do not accept strangers in their homes because they relish phenomenal amounts of company or washing soiled bedsheets. They do it for the money.  When he bought his two-bedroom, two-bathroom condominium in Astoria at the end of 2009, Mr. Naess found himself financially pinched. He is a senior marketing manager at Carnegie Hall, where he focuses on seat retention (“Once we get someone in a seat, we want to get them back,” he explained). His income is not nearly hedge fund large, and he shoulders more than half the mortgage payment on his mother’s home (his sister picks up the rest) in Virginia.  He had a rotation of roommates, before learning of Airbnb from a co-worker and gravitating to ephemeral visitors, beginning last June. He finds he can make more money and still possess days when his apartment is empty of unfamiliar humans.  At first, as a novice host, he listed his room at $45 a night. Just about everyone wanted to stay at his place. He raised the rate to $65, and then to the current $85. He has a two-night minimum. During sluggish winter periods, he shaves his price, and also applies a discount for a stay of a week or more, and a larger one for a month. His apartment is new and clean and there are two bathrooms, so guests have their own. It’s a quick subway trip into Manhattan.  The desire to save money is what puts renters in Mr. Naess’s apartment. Hotel prices in New York average about $300 a night. When Mr. Bontkowski and Ms. Held visited the city a year ago, they spent nearly double Mr. Naess’s rate on a hotel, and they didn’t even like the room. “I asked my boss where do college students stay when they go to New York, and he told me about Airbnb,” Ms. Held said.  Mr. Naess has rare cranky moments when he is fatigued and wants to “sprawl on the couch and watch brainless TV” while strangers he wishes would evaporate are tottering about. He reminds himself that international travelers are paying half of a Virginia mortgage.  The hosting phenomenon has stoked considerable controversy, and it remains a point of contention which taxes (like hotel occupancy taxes) hosts and guests are obliged to pay. New York law prohibits people from renting rooms in their apartments for less than 30 days when they are not present, but a lot of other issues are murky. The state attorney general, Eric T. Schneiderman, who believes that many hosts are violating the law, is battling Airbnb for records of hosts to see what’s going on. Airbnb is trying to get new rules passed and argued in New York State Supreme Court on Tuesday to block the attorney general’s inquiry.  Airbnb charges guests a sliding fee of from 6 percent to 12 percent, depending on the price of the booking, and exacts 3 percent from the host. Mr. Naess gets a 1099 tax form from the company reporting his income. His running tally: $17,958.  Guests may post reviews of hosts on the Airbnb site, and hosts may grade guests (these appraisals are only for fellow hosts). Mr. Naess has received flattering comments and has spoken agreeably of his lodgers. To the best of his knowledge, he has yet to welcome any thieves, smugglers, drunks, Ponzi schemers, arsonists, arms dealers or murderers.  His renters frequently give Mr. Naess a gift: flowers, wine, cake — all appreciated. Mr. Bontkowski and Ms. Held brought him some Bavarian mustard and one evening prepared a goulash dinner. In Mr. Naess’s guest book, Ms. Held drew a fetching picture of the Astoria skyline.  One couple moving to New York stayed with him while looking for an apartment. When they found one on Roosevelt Island, they had Mr. Naess over for dinner.  Two days after the German couple left, Giorgia Mazzi, 27, and her friend Federica Biancardi, 29, checked in from Rome. They were staying for nine days and then going on to Cancún for a week. Both are bartenders and the very definition of exuberant. It was nearly 2 a.m. on Saturday, March 8, when they reached Astoria. Mr. Naess waited with welcoming beers.  In the interlude between guests, he had washed the sheets and towels. When visitors stay beyond a few days, a husband-and-wife cleaning team whips in to spruce up the entire apartment.  Not long after their arrival, the women from Italy wanted to go to Brooklyn. They had a hankering for fried chicken, so Mr. Naess took them to a barbecue place. They started joking about cooking. Mr. Naess told them he made killer pasta, and they told him, listen, we’re from Rome, get real. Nobody cooks better pasta than we do. They decided that in a few days they would have a cook-off.  When you rent from Michael Naess, it feels as if you are staying with your favorite uncle, the one who dotes on you.  His only rules are that you smoke only on the balcony (and deposit butts in the coffee can) and refrain from drugs and late-night parties. He tells renters to go ahead and indulge in his groceries. Make coffee. Use his milk. Eat his English muffins. (Most guests replace what they consume, though he doesn’t mandate it.) He leaves a snack basket in the spare room with granola bars, peanuts and almonds. Often, he offers his visitors complimentary concert tickets he gets at work.  He avoids showering at the same time as guests, so as not to reduce their water pressure. One frigid night, the heater went on the blink in the spare room when a pair of English travelers were there. Mr. Naess traded rooms with them.  As part of the décor, he taped a subway map to the wall near his apartment’s entrance, as a reference for guests. Once he had a Korean woman and her boyfriend who barely spoke English, and it was hard to give them directions, so he resorted to Google’s online translation service. The boyfriend was obsessed with the National Basketball Association and bought jerseys of all the teams.  Months ago, two Brazilian women who stayed with him acquired so much clothing that when it came time for them to leave, their suitcases were bursting. They fretted about the weight of their bags, not wanting to exceed the airline’s 50-pound limit and incur an extra cost. Ever since, Mr. Naess has left a scale in the spare room.  Except when Carnegie Hall shuts down in the summer, he works lengthy hours. He runs two marathons a year, a habit begun in 2003 as a tribute to his father, a marathoner who died that year. This means Mr. Naess is often out running. Each morning, he runs four miles to work.  In some instances, his guests spend more time in his apartment than he does. A review by one visitor characterized him as a “ghost.”  The tang of pasta sauce scented the air. Mr. Naess had the burners on and was bent over a frying pan. He was going with his surefire rigatoni carbonara. The Italian women were countering with saltimbocca alla Romana. Mr. Naess did not consider it a disadvantage that his recipe had been learned from his mother, who is German.  In the cook-off, his meal would go first. The women were taking a tolerant, careful tone, but nonetheless an assured one. “You’re going down,” Ms. Mazzi told him.  “Going down?” Mr. Naess said. “We’ll see about that.”  “Even if it’s better, I’m going to lie,” Ms. Mazzi said.  “Do any shopping?” Mr. Naess asked to change the subject.  “Mamma mia, you have to see,” she said. She brought out a hoodie, shorts and boots, all with American flag motifs. “I love America,” she said.  There was a pleasing frisson among them as they collected at the dining table and sampled the rigatoni.  “This is good,” Ms. Mazzi said. “I hate to admit it.”  “It’s a surprise,” Ms. Biancardi said.  Mr. Naess said, “I went easy on the garlic, because I know you want to go out and talk to men.”  Someday, Mr. Naess said, he expected to get married (adding a second income) and have children, and there would go the spare room, but until that day, this was fun. He was between girlfriends. His last relationship, with a woman from Long Island, had dissolved on Valentine’s Day.  Making conversation, Ms. Mazzi asked Mr. Naess what he cooked when he had a date over for dinner. He told them that he emailed the woman a menu with five choices.  “That’s like on the fourth date,” he said. “Not right away.”  Ms. Mazzi told him that she had introduced Ms. Biancardi to a bagel that morning. Ms. Biancardi said it was phenomenal. She ate it slathered with peanut butter.  Tucking back some stubborn wisps of hair, Ms. Biancardi deftly got going on her dish. Ms. Mazzi said she would clean. Mr. Naess watched stupefied and said, “I would never attempt this.”  They sampled it. The taste suggested heaven.  Who won? They diplomatically declared the dishes so different yet both so tasty that the cook-off would go in the books as a tie.  “It’s one to one,” Ms. Mazzi said.  Dishes dispensed with, the women insisted that Mr. Naess go out drinking, and so he steered them to a nearby karaoke bar. Beer for him, vodka for the women. Mr. Naess sang “White Wedding” and “American Pie,” while the women gravitated to Italian songs he had never heard of. The three collaborated on a faintly memorable “Summer Nights.” Wrung out from singing, they played a game of pool. Mr. Naess won. At 1 a.m., he packed it in. They kept going.  Days after their departure, he received text messages from the beach in Cancún.  Italy had barely exited when Canada entered for five nights, in the guise of a vacationing couple in their 20s from Nova Scotia. They were quirky and vigorously self-involved. Though on their first visit to New York, they didn’t ask for recommendations or help of any sort. Mr. Naess gave them concert tickets to hear the Norwegian pianist Leif Ove Andsnes. Otherwise, they were in and out with barely a trace.  Next, Mr. Naess had five stranger-free nights for convalescing. (“I actually thought of sleeping in the guest room to see what it was like, but didn’t,” he said.)  Down in Washington, Anthony Pietromartire, 25, a robotics researcher at the National Institute of Standards and Technology, had no plans for the coming weekend. A friend of his from France, his native country, was competing in a big fixed-gear bicycle race on Saturday, March 29, in Red Hook, Brooklyn. Why not show up and surprise him? He bounced the idea off a friend and colleague, Thomas Lafarge, 23. He was all in. In short order, they located the beautiful room for rent in Astoria and booked it for two nights. After work, they boarded a bus, hauling along their bicycles for New York transportation.  Mr. Naess greeted them after their late-night arrival and chatted for a bit. The next morning, he had work. The two friends fueled up at a rackety Astoria diner, relating how they had ridden from Pennsylvania Station to Astoria and gotten lost. They asked for directions from a conveniently placed police officer. He had no idea. Done eating, they rode their bikes in drizzle to the Brooklyn race. There would be scores of competitors. They had no doubt that they would find the friend. The frame of his bicycle was made of bamboo. He won the race.  Sunday morning they were gone. Clean, clean, clean. Wash sheets and towels. Add nuts to the basket.  In the evening, Mr. Naess’s next arrivals in his inexhaustible sequence of guests showed up: Valentina Fabrizi, 27, and her boyfriend, Jorgos Kloutsiniotis, 28, from Rome. They would be installed in the apartment until the end of April.  She had recently completed her degree in civil engineering and, wanting to improve her English to enhance her job options, and eager to visit New York, had enrolled in an English class in Manhattan. Her boyfriend, a chiropractor, took vacation time to tag along.  To get them oriented, Mr. Naess had lunch with them one day after her class. Ms. Fabrizi said they would walk around and “see how the city works.” Mr. Naess gave them concert tickets. Mr. Kloutsiniotis wanted to see an N.B.A. game. He said he played “baskets.” Mr. Naess said he could show him a park where he could slide into pickup games. And Astoria, how was Astoria?  Mr. Kloutsiniotis said: “It is very nice. I looked it up on Internet and I knew Astoria was good.”  Ms. Fabrizi said, “It is quite cozy. Not so crowded, but still America. I like Astoria.”  An earlier version of this article gave an outdated name for one country from which some of Michael Naess’s guests visited. It is the Czech Republic, and no longer Czechoslovakia, which was split into Slovakia and the Czech Republic more than two decades ago.  A version of this article appears in print on April 27, 2014, on page MB1 of the New York edition with the headline: Another Day, Another Stranger. Order Reprints|Today's Paper|Subscribe
A Queens resident with a spare bedroom has rented it out over the past 10 months to scores of guests, taking in almost $18,000.