Weighted voting system. The participants would self-police the population after the initial vetting?  Maybe implement some sort of imaging software that estimates composition of a full body shot, requiring a full body shot with adequate lighting to register as a member? Side effect would also be less really poorly lit or super grainy shitty photos that are indistinguishable between bigfoot, a teenager, or a bottle of Sam Adams. How realistic that would be to implement at this point I've got no clue. But I do know beautifulpeople used a voting system. Never used the site myself but I've heard both good and bad about it, but the self policing and voting sounds like a start.