I occasionally play when the mood takes me, although I try and guess what the girl in question would ask for as opposed to what she is actually worth.
For example, there is this really cute Hungarian girl at the Costa near where I work; petite, tanned skin, cute smile and long brunette hair. I would have been happy to pay up to £120p/h for her, but I reckon she would be in a group that charged £80p/h for all girls.
Conversely, there was an English girl I saw behind the counter at a Tesco who was quite tall, with a decent face, short dark hair, relatively flat chest and an odd rash on her neck. I wouldn't go above £90p/h for her but she would probably market herself at £140p/h as a 'student'.