I find it fairly unacceptable (for myself) to receive life needs without a exchange of finances, goods or of services. I find it very unacceptable (for myself) to have that trade be sexual in nature.
I see no real problem with anyone else doing it though - providing that they always feel that they have the power to walk away from the situation. If they do not have the perception or reality of that power (the power to leave), than I find that very victimizing. At that point it breaks down into circles of hell type levels of victimization. Sure you can categorize it, but however you break it down, it's victimizing.

If that all makes sense?