If you don't have a choice to be a prostitute, it has everything to do with it. Forced prostitution is bad enough, but being mishandled to the point of being hurt is worse.
So, you're saying, it morally OK to have sex with someone who's forced to be a prostitute, as long as you're not hurting them?!
I disagree. IMO consensual sex is fine (however BDSM it is), non-consensual sex is bad. Arguing the degree of badness, while sometimes useful, is (1) not relevant to the above discussion, and (2) a second-order effect, so vastly less important anyways.
No. what I'm sayin is that if it is consensual, whatever folks agree to is fine. It doesn't matter to me if someone wants to go through this stuff or agrees to it. There has to be choice. This includes a legal prostitute: The prostitute should have every right to refuse a sex act, whatever it may be.
But when it isn't consensual, the harm done makes the situation that much worse.
