To be honest, I don't think there's any sense in being offended, or taking it personally if a prossie slags you off behind your back, even if you are a regular... Well, actually especially if you are a regular. The transaction itself is grounds for instant judgement from either party. And as soon as you forget this, then you are just displaying symptoms of fluff infection.
If you are making a habit of paying the same woman for sex, all that will happen is, she will build more and more contempt for you. It's not much different from most marriages where the husband splashes a fortune out on his woman only for her to stab him in the back eventually (a woman spoiled with too much attention, is ironically, a woman that is as good as lost). I'd be much more confused if a prossie actually liked me than if she slagged me off behind my back actually.