I've only experienced something similar to this once. I was in LA at the time for a few weeks with work and I booked an incall with a young lass off the internet (by the way, LA is a nightmare for punting - so many fake adverts and scams, it took me a few goes to find an actual escort!).
This lovely girl, called Ava if I remember correctly, was a really bubbly bundle of fun. She charged $300 per hour, but we got on well and chatted for about an hour and a half on the first night before having sex. She then was happy for me to stick around and have a second round. In all, I stayed for just over three hours and left feeling very pleased with myself.
A few days later she called me (another weird thing about LA - the girls always seem to call you to ask for repeat bookings, which really took me aback) and said she would halve her fees if I wanted to see her again. I jumped at the chance but did wonder why and asked her when we saw each other again. She said that she charges more for people who are unpleasant (she actually said that one guy was such an 'asshole' she charged him double) and was happy to charge less for an easy-going guy like me.
I took this at face value, had another great time with her (the first girl I'd ever managed two rounds with) and stayed about 90 minutes rather than the hour, for just $150.
Shortly after that my little business trip ended and I never had the chance to see her again.