If she made an agreement with him to have forced sex then in my opinion there is no sex crime because she consented and she accepted his money and I think that she would have a hard time proving otherwise. However,if she refused the money it would have to depend on her reasons for her to do so, anything could have happened for her to change her mind, he could have become very aggressive and violent so whether she agreed to it in the begining is not the issue, it's the events that actually took place after the agreement was made, so yes a crime could have taken place that led up to her not taking the money thus ending the agreement and her being a prostitute should not mean that her complaint should not be taken seriously, she should have the same protection from the law as anyone else has. My dad is a Barrister and he has sent quite a few men to prison over the years who have raped prostitutes thinking that if they said the woman agreed to it they could get away with it because who is going to believe a prostitute.

if she would have not taken the money she would possibly had a case, but being a prostitute isn't the best for being a witness