Otakon '07 was my first con and my first time cosplaying. I got a rose from some random guy who I think thought I was a call girl (considering my Chibi Urd outfit was a bit slutty), other than that, though, no one really bothered me. You get looks, but no one approaches. At the McDonalds Saturday morning, the waitress asked my friend (duelistbluerose) what character she was and how did she make her staff. No problems.
Besides, you have to scare the grandmas every once in a while. The DC Anime Club has cosplay contests and demostrations and we often run around the city still in cospla