I'm always reticent to talk specifics on the phone because of the disclaimer you mention. But I always check for reviews and do's/don'ts on a website. My experience, I've found a handful of girls who do it for me. I'll try out some well reviewed traveling girls and make my own determination on a return visit. I do find traveling girls are less inclined to cum because of the overhead of being on the road and wanting to be functional.

I do often hear complaints about "VIP" service which for many girls is cumming. My view - don't visit those girls if you don't want to meet their price. But also don't complain that you aren't getting what you want if you do visit and don't want to pony up the extra.  

My advice:
(1) Read reviews - getting VIP service is pretty short money in order to save a hobbyist of bad experiences
(2) Really read the reviews - there is an awful lot of exaggerations contained within the reviews (An awful lot of reviews have very large cocks and they are surprised the girl can handle them).
(3) Experiment with "new" girls without reviews at your own peril.
(4) Find some local girls who can be a go to for what you want. Maybe they aren't a 9/10 on the looks scale but if they provide a good service, I think that outweighs a super hot girl who only goal is to get you out the door.