I completely buy your morning/evening shower argument and I'd add that the social pressure to smell "nice" begins in middle school and is so intense that you have to be Brad Pitt to dare to smell bad. But living in a city that is a lot more densely packed than most European locales, I can't agree with your "3X the nose distance" theory. Except for the homeless (and every once in a while, a recently immigrated cab-driver), New Yorkers almost never smell. And this is a city where a huge proportion of the population is foreign-born!