I read this but did not have enough time to comment and share my personal thoughts.
First, Let me say I think I understand what you mean (which is sort of be a smart customer)
Second, personally I do not go over specifics or service details. I just get a feeling of the rates. If it's above average. I simply and politely move on.
Third, if I find a girl I'm interested in staying with her. Then I just ask smoothly general service questions
Fourth, my brain is focused on what she say, how she say it, pick the signals,...if I get mixed signals and I really like to stay then I'll stay...if I get a mixed signal and feel she is intentionally doing it then most likely I won't stay...An example our rates start at 300hr then without the need to ask for specifics that's the basic...then sorry I gotta move on.
Fifth, experience helps a lot at and through out the meet, greet,...decision making and the session. There is no specific and exact rule or formula. Just be smooth, funny, cool, make efforts as if she is a date which she is.
Sixth, definitely a well-reviewed not YMMV girl is an excellent pick.
It is a multi step procedure relying on your instincts which is unfortunately is a bit mis-guided. That's why I try to make my decision without the sexy presence.
These are personal thoughts/opinion..
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"Difference in opinion does not constitute animosity"
W K Neoh