On the Old Guild I never had any problems, and on the New Guild, unfortunately, I haven't yet been able to RP, so...

I had one site where I had the GM quit his own RP because he said my characters, basically, weren't responding to their "situation" the way HE thought they should. And another site where I actually had to quite literally "drag" another person's character out of a room because she refused to do more than use dialog... her character just a disembodied talking head floating in a detail-less void. Even though that wasn't what her character literally was. Yeah, I write nice, detailed, "living" posts, and all I got back was one-liners.

Oh, oh... had a story of my own I GMed, a restart of an RP that died due to a very main player leaving the site. Only, the one person I got interested in the RP was... terrible. His first post started with his character getting in a fight, and devolved from there. I can only shudder...