I feel bad for adults who decide to get braces.  Most of the rest of us dealt with all that when we were awkward teenagers, when life was messed up to begin with, so the added annoyance of braces was like an inevitable rite of passage.  But adults with braces have to sort of adjust their life temporarily to this new facial contraption that's impossible for people to ignore.  So every conversation includes an explanation of why they decided to get braces, and every picture shows them awkwardly trying not to show their teeth when they smile.  Plus, there's the tendency to associate braces with teenagerhood, which means there's no way anybody will take you seriously.