I've never met an escort who actively requested either oral or rimming. I'm usually up for it if the girl is attractive, and they rarely complain, but when I don't I've never been asked.
It's really puzzling when they try to charge extra for it though. I'd never hand over more cash just to give them extra pleasure, that just seems totally backward. On the odd occasions when this has happened I've just gone without, and gone straight for the fucking, but it does tend to ruin the atmosphere.