I'm all for this. I cover a lot of anime conventions, and I have seen and experienced first hand some creepy, disturbing fucking shit. Here's two quick stories off the top of my head.
Ohayocon 2009: A girl maybe 16 years old comes knocking at my friend and I's hotel room door. I open it up to find her with a Snapple bottle filled to the brim with straight up Jack Daniel's. She asks if she can come in to "party." My friends and I are all 20+. I closed the door in her face.
Matsuricon 2010: A meet up with a group of people who my friend knows with the intent of staying in their nice ass hotel suite for the duration of the con. I never met these people before, and even my friend admitted he didn't know them that well, but the offer was too good to pass up. Upon arriving the owner of the room pulls out a giant bag of Ecstasy and says, "tonight is going to be a good night." I'm thinking, "Ecstasy at an anime convention with underage people isn't a good idea..." and instantly consider leaving, but my friend insists everything is cool. Later that night a couple of the people from the room come to my friend and I and ask us to recruit girls for a hotel party. I'm looking around, and all I see are young teens, some of which are with their moms, and I'm like, "Dudes, wat?" Then one of the guys comes up to me, gets really close and starts talking low about how he likes them young. Even my friend realized it was time to leave at that point. We drove out of there as fast and as far away as possible.
There are plenty of other stories too, like how a guy tried to rape a young girl on the steps at one con I attended, or how one of my "friends" thought it'd be a good idea to go around the con and sneak upskirt panty shots of girls, while later trying to bang my friend's 13-year old sister.
I'm not saying anime fans and nerds are generally creepy (I'm not a creep, I think...), but it's definitely an environment that seems to attract that kind of shit from all of my experiences. Not to mention the girls often don't help the matter any by being genuinely slutty, beyond that of simply attention whoring (see: my first story).