Let's be honest not everybody is articulate and engaging in starting blogs and such (like me), if anything some people may just enjoy the pretty sights and colors. For that it's forgivable, but there's another element that should be scrutinized more, the trolls that pretend to be girls just to get hits, making up film or historical figures as members, and people who are more oriented toward other interests such as music.
For most it's simply the myspace spill over, and perhaps the problem is that very mindset of just getting another free page on the web.
Suspend all inactive accounts ---six months or more of inactivity means the person is not interested in being part of the community.
Dump the fetish trolls that make up members of the female sex or some other figure (get a life asswipe).
Don't offer invites, serious members only.
It's ok to be a passerby if that's what's more interesting, just don't be dead weight.