For the most part, New York City is laid out like a grid, which means there is zero excuse to ride the wrong way down (or up) a one-way street. At worst it requires going a block out of your way, which, if you're already on a bike, shouldn't be much of a hardship. And salmoning (word to BikesnobNYC) is one of the worst bike-related offenses there is. No excuse.