Right - one odd thing alone isn't enough. I worked on a platform that allowed contributors sign up and provide content from their area. A user provided some fishy content with a very heavy slant so I started looking into his profile. The big thing that really confirmed we were on to something was his profile photo was one of a retired athlete. Busted by tineye.com. Once we dug in some more we found it was a local politician writing under a fake name.

So yes, having all your friends in another area doesn't mean you are a fake, but it may be an easy thing to look for that flags the account for more inspection.