The only thing I would say is that, if you do want to take pot luck, sometimes you can end up with some really attractive EEs. Their services vary from some brilliant ones to some average. They operate mainly out of hotels around the country. I do take a chance once in a while and majority of the time end up with a decent punt. I'm no expert on this but I tend to rely on my experience regarding who answers the door and negotiate my punt there. Usually then go for half hour. There have been occasions where I've visited one on three consecutive days because she was so good to me.