I haven't heard of them, but upon looking just now, I see a few stolen photos, a lot of "cosplayer photos" which are usually stolen, but are hard to tell, and a lot of photos that look like they could be stolen because of how they are. They look very similar to other photos if not the same. It's really up to you, but they look pretty sketchy to me..
Cosplay DA Regular DA
Kumoricon 2014 (so far):
-Sora (Kingdom Hearts 2)
-Serena (Pokemon Y [It's the one I have lol])
-Akaito (Vocaloid. Black & Red Ver.)