This is a special place to have sex. Space is limited (well, not when you are in the main room ... Line I had to once ... Sorry in my book), lots of people coming in and out ... And at least one of you (but valid for gay couples) isn't at the right place.
I love to have quick and savage sex in restrooms. It's hot, it's passionate... It can be noisy... Who cares.
Summer toilets are nicer than others ...I like airport ones but from time to time being taken in a trucker stop toilet makes me feel like a slut ...