If at all, not very. It’s a contractee’s responsibility to uphold his contracts, not the responsibility of the businesses he frequents (unless something else is involved, like fraud). And sexual relations are a byzantine business with very diverse standards and circumstances (e.g. some spouses have permission, others have cause, and for yet others the need-to-harm ratio is not that severe).

But that’s IMO. I suggest waiting for Yemisi to post an article on sex work and then ask her this question.

If a “sex worker” does business with a person who she (or he) knows is married, would that be an immoral act?