I am one who generally tips before the session in hopes that the session will go well... As you said, absolute insanity! I then have no idea if the service I got was because I was so fresh and clean, because I was so polite, or if it was just because I tossed another 20 in the envelope...I tip because it is a VERY personal service, and if they have pleased me, they deserve a little extra. Sometimes I will tip the first time, because I don't know if I will be a regular of the girl or not, then when I repeat I wont tip every time because also being a repeat is a good tip too. Mind you there was a girl I saw over 15 times that I tipped every time, somedays more than others, because of the incredible service she provided, and how comfortable she made me feel. This is a human service, yes when you pay $250/hr and are unsatisfied it can very disappointing, but the girl that put her self through that for you should always be treated with respect. Yes, you probably won't tip a surgeon on a $5000 surgery, but you might tip a tattoo artist on a $500 tatoo, or a hairstylist on a $50 haircut, because they did a great job and made you look good. Well these girls made you feel good, isn't that deserving of a little extra?