You can also tell by what they put in their essays. It might take a little bit, but you will figure out how to tell who is real and who isn't.
Excellent point. In the essays, the fakes won't fill out very many sections and have things like "ask me" as the answers. Most real women put forth a genuine effort to communicate and are successful. Another clue is British spelling, words like "organisation" of "colour" for example.
On the main profile look for things that don't make sense like the woman describing herself as slim yet listing her weight as 250 pounds and often prefer men from 18-45. They also cite that they definitely want children. This sentiment will also be expressed in essays. Real women do not openly come out and say that they are looking for the father of their future children in their essays.