Honestly, it is hard to tell the fakes. I'm on apg, and used to be on Swing Lifestyle, and got accused of being fake a fair amount. For no other reason than I have professional looking photos up and am an decent looking 20 something single woman.
So, while I agree there are fakes (I ran into a lot on Swing Lifestyle, particularly single women), you really can't assume most of the time.
That being said, occasionally there are some really obvious fake profiles, and those are usually worth a laugh or two, lol