Answer with free mind. It's just a discussion and I wanna know everybody's point of views :)
a rel='nofollow' href='https://www.facebook.com/help/167722253287296'https://www.facebook.com/help/167722253287296/abr /refer to this link it may helpful
If they are not updated their profile details(like education job and etc.,) check the friends list of their's and this will not completely eliminate while choosing fake profiles just a precaution. And dont do much conversation with them...
There is already face recognition technology in Facebook so it can take a live snap of the people before creating the account. If it matches the existing one, FB will know that its going to be a fake profile. Else than that the inactive accounts must be monitored and the ones whose activities are rarely linked with their friends on facebook.