Part Humiliation fetish, and part of another fetish that has to do with FFT. That said, if someone is asked what flavor of ice cream they like, they can offer a detailed reply, but in the end, it comes down to We like what we like. Having a preference for Chocolate ice cream does not mean one hates strawberry, its liking what one likes. And in the end, a subbys pleasure depends on if the Domme finds pleasure. Otherwise it becomes "You do this, i do that" engagement. So I am curious, outside of the obvious, does facesitting a sub bring You pleasure?