This scam involves a series of messages supposedly to warn people of others reading their Facebook profile and offering a way to see who they are.
e.g. “Guess who viewed your profile?”
or “Guess who has unfriended you?”
or “Guess who wants to know more about you?”
Usually these scammers are offering an APP or a service to let you see who has read your profile and charge for that of course.
But Facebook have repeatedly said that there is no way for any APP or similar to access that information, so it’s fake.
Facebook do shut down anyone making these kinds of claims, but that takes time and in the mean time people have fallen for this.
If you have any experiences with these scams do let me know, by email.