I've been using all kind of adult hookup sites for four years. 99% of them are a WASTE OF TIME! That being said there are a few adult hookup sites which are worth joining (but just joining won't get you laid). From my experiences I can recommend 3-4 adult hookupsites: BeNaughty.com is one of them - also try CasualDating4u.com (absolutely awesome when being used with a good strategy), Adultfriendfinder (hit and miss but mostly good results possible).
Why I consider BeNaughty.com one of the best adult hook up sites? Well, if you decide to upgrade your membership the prices are decent and dispite the average review claiming that there are only fake profiles, my experience has revealed that you can met REAL women for casual encounters.