 Why might the narrator feel that he is "so dirty, so very dirty that I could never get clean if I bathed every hour for the rest of my life"?
I admit it: I didn't know if I was coming or going—but I know that if I stuck to the old man, I was a comer ... even if he was a goner! The golden Moon and the silver ship, symbols of greed. If a half dozen winos in Seattle hadn't helped me get them loose, Doc and I would have been wanted for the murder of a North American Mountie. All my great-grandfathers have it. I told the human no, thanks, and walked Doc toward the flophouse three doors down. It had happened a few times right after I first found him, but now it was worse. I tried not to think about it and helped Doc through the fly-specked flophouse doors. Lucky that I never needed to shave and that my face was so dirty, no one would even notice that I didn't need to. They told everything I needed to know to become the most powerful man in the Solar Federation. When I got to thinking it was just a dream and that I was dragging this old man around North America for nothing, I remembered who he was. I remembered that he was somebody very important whose name and work I had once known, even if now I knew him only as Doc. He shut up at last and I laid him down again and put his arm back across his face. I don't know why, but nobody will help you if they think you are blotto.
 Because he unknowingly feels debasement in desiring something material.
 Because he is homeless and unclean.  Because he has cooties.  Because his addiction prevents him from bathing.  Because he unknowingly feels debasement in desiring something material.