Bad ones such as? Which con might I add? And did any key staff happen to be fans of his? I've had first hand experiences with the Mangina at Anime Vegas 06, he ruined the con for a great deal of staff and volunteers and he's been banned ever since. He was extremely rude to the entire staff and especially the volunteers, acted like he was Brad Pitt and should be treated as such, he even brought a couple of the female volunteers to tears (hey that rhymes) because of how rude he was. And no Vic just because they are girls that like anime doesn't mean they are absolutely in love with you, that doesn't mean you can show up and invade their personal space and touch/hug them in anyway you want without asking.
However if you're a fan of his then he's a pretty nice guy, especially if you're a chick.
Just ask /cgl/ or coscom they'll give your horror stories of the Mangina.
I'm Guest Staff for Otakon. Been doing it since 2000. And I used to run autographs up until a year or two ago. So if you didn't get an autograph, you can lay the blame at my feet. We've had Vic twice I believe, maybe 2004-05, and 2007?
I tend to stay out of other cons business as it's better overall, and the only other con I attend is the occasional Katsu as I'm in the area. So I was unaware of Vic's rep.
But yeah, Vic seemed like a nice guy overall in his time at Otakon, and only had one random request to let a couple of his fanclub members take some pictures with him. Otherwise, there wasn't much to ketch about, though it is entirely possible that he may be worse. As far as Otakon goes, we've had some divas, but overall the guests are decent people. I'd rather not go into whom, since part of my job is relations, and saying stuff about them probably is not in my best interest if we want them again.
But we've had guests leave us short in autograph lines for signatures, and we've had guests stay way past their due date to finish off a line (TMR and Scott McNeil spring to mind for the latter). We've had guests burn through alcohol at guest dinners, and we've had some who have been relatively hands-off. We gave them their stipend and schedule, and they took care of themselves.
It's hectic at con, but rather a lot of fun looking back afterwards, which is why I continue to do it.