Once you are popular, like 7-Eleven, with thousands and millions of Fans, you will get a lot of graffiti on your wall. People and Pages seeking attention without adding value to your Brand and your Page will inundate your wall every day. Brands can’t simply disable ‘User’ posting because of graffiti though. That would be taking Social out of your Social Media properties!
Page admins should regularly clean up their wall of graffiti and warn users to stop indulging in that kind of behaviour. Exactly like moderators on public forum sites do. Otherwise, you’ll accumulate so much graffiti, your page will look like a scrap yard!