It sounds like a lot of this stuff happens at bars during events, not at the events themselves. How common is this behavior at bars in general, independent from a hacker con? Also: some of the girls that I know who are hackers are offended at the idea of red/yellow cards. The implication there seems to be that they're helpless, and need somebody to swoop in and save them. That, at least to some of my girl friends, is…
Instead of the red card if someone touches you inappropriately why not slap them in the face - hard.
Still I'm sure some people will abuse this system like any system and lets face it the audience will not exactly be angels in not abusing any form of system. Lets face it, in Football it's not exactly perfect. Unless all events are video'd to death and can be verified then it is abusable. That said how long until somebody does a erect nipple/penis video recognition system, scary thoughts on many levels.
Today red cards, tomorrow video survalence and full location tracking with all your comminications monitored so you can be at a event were people complain about privacy.
There again I thought sexual harrasment was a against the law and that carries more weight than any token scoring system that trivialises the offence.