Heh, we saw some guys like that at AnimeBoston. Some VEY strange looking folks, but apparently very well behaved, according the the concierge at the hotel where it was held. He said the S&M convention the previous week was kinda wild. ;o)
There was a now-legendary incident at an SF con in 1997; by way of disclaimer, I wasn't there and have only read accounts of the incident posted online. Anyway, apparently there was a mini-convention of S&M enthusiasts within the main convention; these were SF fans who were attending the con and planned a "get-together" in one of the suites to celebrate their, uhm, *other* interests. The party progressed, and some folks left to their rooms to pursue more private activities. One such couple decided that the exposed sprinkler system pipe running along the ceiling of their 4th floor room was in just too handy a location to pass up. They discovered, to their chagrin and to the chagrin of much of the rest of the hotel guests, that the pipe was not designed to support the weight of a human being.
As a result of the pipe breaking (at 5:15 am Sunday morning) their room was flooded, all of the rooms surrounding theirs were flooded, and most of the three floors below their room were flooded; also, because of the sudden change in the water pressure the fire alarm went off, causing the entire hotel to be evacuated. At 5:15 am.
Despite the excitement, the con continued; Sunday was the last day of the con, anyway. However, the hotel declined the opportunity to host that SF con the following year. ;)