Because anyone can lay there and receive cum by multiple guys who aren't even actual porn performers. There are a few marginal mopes at best, but bukakke boys are one level up from living in a box on the street. Really, this isn't about morality or impurity. It's about the social strata in porn. Notice the girls who do bukakke are those who are on their way out, grabbing the last quick money off the tree OR they're sub par looking new girls that don't know any better and figure what's the difference between 1 Manuel Ferraro cumming on them vs 50 parolees cumming on them. But that's the beauty is bukakkes to me- the back stories. Then, there are the rare true cum sluts who truly love pushing their own boundaries to out-nasty themselves, and the is Ava Devine, who is truly the happy hooker. She will take you on, chew you up, all with a smile on her face and make sure you got home ok the next day.

The other two questions I answered last post. Hope that helps