A farmers' market in Stroud … is flavour really the issue? Photograph: Nick Turner / Alamy/Alamy  Eating local produce, in season, is a lovely notion. While it was once the natural way of things, it is now a trend. And as such, it has reached that point at which the backlash begins to gather apace. The mantra has started to sound like hackneyed PR schtick. The legendary London greengrocer Andreas Georghiou tells me: "It's very nice talking about it, but everyone I encounter who has a shop and says, 'We're just going to do seasonal," it's more of a marketing gimmick than their own personal beliefs."  Last year the Observer's food critic Jay Rayner slapped a swift nail in this particular coffin when he set out to discover how a sustainable food chain might look in the coming years, and concluded that local, seasonal produce is not a solution but a middle-class lifestyle choice. Are the assumptions cheffy types proliferate about it being the route to superior taste also unfounded?  I'm beginning to wonder. Long before spring sprung this year, my brilliant local greengrocer had in some attractive mini crates of king-sized strawberries. Pah, I thought. They'll be all fur coat and no knickers. But then someone brought some round as a gift and they were delicious.  The main reasons for local, seasonal produce tasting good are that it's grown in optimum conditions and it's fresher because it reaches you sooner after being harvested. However, says Georghiou, "it's such an ambiguous argument. You can have an English strawberry that tastes like water because it's not a particularly good one, and then you get a French gariguette strawberry that is consistent and amazingly sweet. So it's not just about provenance, it's about the specific product." Or as Charlie Hicks, a fellow costermonger who, like Georgiou, made his name supplying top London restaurants, has it: "local is not an excuse for rubbish – you have to take it on a case-by-case basis."  Georghiou's guess is that my giant strawbs hailed from Spain. "We haven't had a winter anywhere," he adds. "It's been very mild and very wet, so there's been some very good early fruit." Many of the British strawberries in supermarkets at the height of summer, on the other hand, are cultivated and packaged primarily to ensure a long shelf life.  Some fruit and vegetables improve with age. "Things such as peppers and aubergines from Spain and Italy tend to taste a little bit better when they're slightly mature," says Georghiou. The flavour won't be impaired, he adds, "if they're three days, five days or even 14 days old." Apples, of course, store well and russets are widely believed to improve over time. "They were popular with the Victorians," says Hicks, "who said they were better after Christmas, when they develop a more marzipan flavour."  And here lies one of the most obvious hypocrisies of the local, seasonal trend. Many of the foodies who bleat on about it could not countenance living without things like lemons, figs and galangal. "This is northern Europe," points out Hicks, "and there's lots of stuff we can't grow. What about the glorious alphonso mango?" Shelina Permalloo pretty much won MasterChef 2012 with imported mangoes in recipes inspired by her Mauritian roots. Of course, she says, "freshly picked mangoes taste so much more fragrant and aromatic", but you don't see her shunning the fruit back in Blighty as a result.  Georghiou shifts five to 10 boxes of English asparagus daily during the season (eight weeks starting around now), versus one box a day of Peruvian imports out of season. For good reason. As Hicks says, "by the time it gets here from Peru, a lot of the sugars will have turned to starches so the flavours will be very poor. If you get lovely fresh English asparagus, it will hopefully be in your tummy within 24 hours of being cut." Georghiou doesn't rate the Wye Valley's attempt to manipulate the English season with their autumn asparagus. "It doesn't taste of very much," he says, "they're only in their third year but I'm not a big fan of their asparagus anyway – we tend to go further north where it has a much better flavour."  This obsession with local has fuelled the rise and rise of the farmers' market and farm shop. In an age of scepticism about supermarkets, buying direct from a grower can make you feel warm inside, if you can stomach the prices. (Although, beware the sellers who didn't grow it themselves: "You see a lot of people in the markets from farmers' markets," says Georghiou. "but they give the illusion that it's a farm shop.")  An interesting study was published in the journal Appetite in 2012, which saw farmers'-market shoppers asked about how the food tasted. None of them could confidently assert that, or describe how the food tasted better. They used vague psychological terms like "getting a sense that", or "perception". One subject blithely said that they assumed the food tasted better because that's what the media kept telling them. Others said the food was more appealing because it wasn't mass produced, so they trusted it more, and thought it of higher quality. Flavour didn't really come into it.  I often wonder whether the unfathomably superior tastes I attribute to home-grown veg come from my heart rather than my taste buds, but Hicks assures me that it'll be because the food is picked at peak ripeness and eaten immediately. When shopping, though, surely the way to get the best produce is to find a great supplier and give everything a squeeze and a sniff before you buy, rather than blindly looking for the "local" label. Where do you stand on the issue?  • This article was amended on 22 April 2014. The sugar in asparagus turns into starches, not carbohydrates, as originally stated.
Amy Fleming: Going for fresh food produced in your own area is a nice idea – but does it have more to do with feeling smug than actually eating better?