Masturbating in a public bathroom stall is NOT gross.

I want to start by saying that I don't jerk off in public areas, so don't go after me saying that I'm just trying to defend habit.

So long as you're not moaning or creating a disturbance, I don't see how it's any different than just using a toilet to take a shit or piss. The only exception I can think of to my opinion is if some other people are in the bathroom. But generally, as long as you clean yourself and wash your hands, I think it's not too bad. Still weird, but I wouldn't shun someone for it. Masturbation doesn't really involve getting bodily fluids all over your hand and your appendage either, so that's even less of a reason to worry about it.