Been going to AMPs on and off for about 15 years now, but I guess I've been pretty naive about information sharing among the masseuses.  A couple of months ago a got fantastic service from a lady at an one of the more popular AMPs in town, so I gave the lady a little extra tip to show my appreciation.  When I visited the place again recently I got a great massage and left my usual $ tip.  The young lady (who is drop-dead gorgeous) gave me a sad, puppy-eyed look and asked me why I didn't like her.  When I asked what made her say that, she mentioned the tip I had given on my previous visit.  Since the lady I had seen previously was not working that day, I concluded (correctly as confirmed by the masseuse) that all the ladies share customer tip information with mamasan.  I had no problem increasing the tip, just thought I'd pass on this info...