This is a distasteful subject, but I'll just mention it and be done with it. I've ridden on underground subway systems all over the world -- Paris, Boston, Berlin, Prague, Washington, D.C., Barcelona, London, Zurich, Rome, Munich, Frankfurt, Firenze -- and New York's subway system is the only one that has a serious problem with homeless urine stink. Okay, I might have encountered one or two faint whiffs in the Paris metro, but it's not a regular thing there. You can, on the other hand, absolutely count on The Unpleasant while waiting for the IRT, IRT Lex, R or IND trains in Manhattan. Is it because homeless guys in Barcelona, London, Berlin and Prague are slightly more sanitary? Is alcoholism less of a problem over there? Do the overseas subway systems use more effective (i.e., more fragrant) disinfectant or employ more clean-up crews?