Its the same case with massage parlors: they either have very well-trained masseuses and take cards, or they are just brothels that may or may not actually give you a massage. I don't think its a bad thing at all...but I can't imagine the working conditions are always great. The thing that makes people uncomfortable about prostitution is the idea that some of the girls might actually be doing it completely willingly (they might even be enjoying it): I don't think the problem, then, is with the existence of these types of establishments, but the complete lack of regulation.