if you're a hedonist, the answer is "giving pleasure". And there's one thing both sexes associate with pleasure.... CUM!  Most of us who can go either way will agree that cum is like coffee or beer... they're all acquired tastes.. and they're all addictive. ;-)  Every jizzjunkie starts out for their own motives.... what was yours, dear reader? For me it was rebound/revenge on a crazy ex... and location near a red light district. ... 

  That brings to mind another turn on...  degredation.. dirty feeling of sex with random strangers. This IS part of the allure to being a prostitute,  but I've frequented places like bathhouses and glory holes because I like the attention being naked gets...  but being fucked by strangers in a pump and dump club makes you feel sexy and dirty... showering doesn't clear out the insides, so you leave with cum breath and cream pie from a bunch of guys... THAT is a hot and dirty feeling.