Not something I would do, and yes it's fraught with problems, but to each their own.
The matter of the power differential does concern me...but that's the case with many relationships: one partner works and one doesn't; one has family support and one's from overseas; one has a serious illness or injury etc. etc.
Completely agree with all those saying that respect has, or should have, nothing to do with sex/work etc. It's this kind of attitude that leads people to argue that it's not REALLY rape if you rape a sex worker...slipperly slope to victim blaming etc. Everyone and every body deserves respect, always, regardless of how you feel about someone's choices.