Clubber
We are an agency, 100% of the clients pay the same price. We collect at the end, so the girl doesnt know in advance if she's getting an extra tip. So theres no way to be influenced, as you suggest, to think a client is nicer than he really is because he is generous.
My post is my experience and that of our staff. In general, the clients who are the most demanding, who you work the hardest to please, who want extra this or that, who go over time, have toilet paper stuck to their behind, or whatever it is that makes them your not so favorite, are generally the ones who dont leave an extra dollar. The clients who are polite, clean, respectful, and appreciative, who we are grateful to have back under any circumstance, will usually also leave a nice tip. This is the reality.
You are comparing service vs. price at different agencies with different fees, Im comparing clients at the same place, paying the same fee, receiving roughly the same service. I make no argument for paying more to get better service, a provider should attempt to deliver proper service for whatever fee she charges. Im sure more than a few of the high priced girls have overestimated the worth of their service.