Beauty Does Not Translate to Great Sex
The problem is beautiful girls, 9-10's, Thai or otherwise, is that they don't really need to try hard, at anything. They don't have to actively seek out a guy, nor want to please them (unless they are in love) as they know that guy is not their only option. They can pick and choose from the plethora of rich dudes available and most will be little puppy dogs waiting on hand and foot to these girls.
Now, there are beauties that are in the industry who are seasoned and provide all the services a guy may desire. Rimming, anal, BBBJ, etc, and they come at a price. These are professionals. For the non-pro hi-so girl out and about town there is no incentive at providing such services even though she is enticed by P4P to make some money. They deem that being with them, seeing them naked is reward enough.
Now its all about your environment. I have been very active in the NYC P4P scene and there are drop dead gorgeous girls who will do what you want, when you want it, if you have the deep pockets and can accomodate them at the Plaza Hotel. Just take a drive down to Jersey and you will find the same hot girls, who will do everything you want at a fraction of the price for longer at a Best Western Motel. Environment plays a factor. Thai culture is very judgmental and a lot of hi-so thai girls will not want to be seen with foreigners. Even though they may be P4P they mingle within their own circles. It comes with the territory.
I have a lot of Thai girl friends who used to work with me in NYC. Girls who dated black, white, asian, indian, latino, etc. When I meet them in Thailand they explain to me that no moderately successful Thai man would see her a GF / Wife potential if they have dated / slept around with other guys of other races and even though they have that freedom outside of Thailand, they are stuck in the cultural warp that so controls their life in their countries.
So these hotties all over Bangkok will be fair game and a easy lay if they were plucked out of that environment. I don't think we should read it as an commentary on how they view foreigners. This is apparent in every country with deep cultural traditions that has dictated societal norms for centuries and more.
I would much rather get the sexual experience of my life then be stuck with a hi-so hottie who is a door-knob in bed. This is only good for impressing your friends, business partners and being the envy around town. It ain't going to matter much once they burn a hole in your pocket and you have nothing but unused condoms to show for it.