Ive travelled to over two dozen countries around the world, and here are a couple of things I've found to be true in my experience:
1. Hard core pros will Phuck almost any guy for the right price. But almost any girl will Phuck the right guy for free. Sexual attraction is a powerful thing.
2. In a fixed price (no negotiating) p4p location where money is no longer the Great Equalizer, such as Angeles City Philippines, the girls choose the clients just as much as the guests choose the girls. Looks, game, grooming and age matter ALOT. Cranky old farts still get laid, but the 9's and 10's are hard for them to get. If you have game, take reasonably good care of yourself and show the girls a good time, those 9's and 10's come over before and after work to screw you for nothing more than hard dick and bubblegum. Not to mention the bounty of local non-p4p trim you find at the mall, discos, restaurants etc.
3. Most (all) girls want a boyfriend, or at least a BFE. Even whores. I've had extended flings with working girls where I didn't pay them for any of the crazy rabbit sex we had, instead I played the BF role. I took them on dates, hung out with their families and friends, played with their rugrats, played house with them. Often the girls paid for some dates, bought me gifts and cooked for me on the regular i made them feel good and didn't sweat them. Most working girls need to feel like they got a good man just like any other girl.
sorry if some of this is off topic

Vince