The courageous Gail Carriger comes out and says what needs to be said. Folks, don't wear pajamas to conventions:
It isn't all vitriol and shame - she offers tips & links to snazzy, geeky fashion advice. We all don't have to look like Lord Akeldama, but, as she points out, there's still no excuse for an 'untended beard'.
You are disrespecting the authors and presenters (if you're a fan) and the fans (if you're an author), not to mention all the other important individuals who have arranged for and attended the event (con organizers, editors, agents, producers, actors). Most importantly, you are shaming yourself and the SF/F industry as a whole. Yes you are. Suck. It. Up.