At first I thought it may be an untapped resource so I checked one out. It's a sausage fest and the girls get too many messages. I did talk to a few chicks on it though (pics were hot) and actually met them in real life (coincidence, one started working across the street and one started working where I was) so I can confirm that there are hot girls that aren't hookers on these things.
More trouble than what it is worth though, easier and more fun to just hit the bars/clubs.