Get off the train in Grand Central... mmm...smell that musty train funk (don't get caught in a Metro North car with a bathroom- you'll be smelling something a lot more than musty).
Walk into a subway station... mmm...smell that faint (and sometimes not-so-faint) vomity/uriny aroma...plus some other kind of subway train funk.
Walk in the streets-- smell that:
- Diesel oil/exhaust
- rotting garbage vomity aroma
- mystery street steam funk
- all of the above if you get too close to a bum, plus a few other stenches