I'd be willing to bet there are several reasons; firstly that in bars people often loose their ability to aim at the urinal. Either through intoxication or just because they couldn't care less if it goes in or not.
Secondly urinals smell stronger than a regular toilet because they're not full of water or anything. The pee can just sit around on the surface stinking up the place.
The final and most likely reason however, is that you are frequenting less than classy bars.
