On CL always make sure a girl posts a picture, run the picture through the internet to make sure it isn't a fake, make sure her call name and age and rates stay consistent. After seeing her ad for a month or so, it is safe to say she is legit. As for the service and prices? Well, you'll never know that for sure without a review or two.
The only exception is the micro-asians. The micro-asian are really loose with that information but that is just the style. They always have a different country of origin or that they are leaving in 4 days (for 4 straight months). Just ignore it. Most of them are legit.