I just made a list of the conferences I've attended. For tech conferences in general, I've attended 15 in the last 3 years. 9 of those were specifically related to FOSS.
1 of the FOSS conferences was the one with the "surprise kiss." I'm inclined to include the guy who insisted on following a friend and me to our hotel room until we went to fetch security guards in the category of a pretty bad one too...which would make 2 out 15 conferences I've attended total to have had a high "ick" factor. If fetching a security guard is justified, it's crossed a line.
If I include things like distasteful presentations (undressed women photos, person on stage mooning the audience, etc) and the example I gave in the interview of being told someone was agreeing with me "because if he doesn't, he won't get any tonight" (I said "implied," but it really wasn't so subtle, eh?), and the creepy guy (note: he was conference staff of some sort) who tried to ask me to be his mistress (???), then it goes up to 6 out of 15, with 2 out of the 4 additions being at FOSS-specific events.
(Oh, and none of these was Defcon or Black Hat. Their reputations precede them, so I will not be attending them any time soon.)
Bad enough to need security guards: 1/9 FOSS and 2/15 overall
Total incidents: 3/9 FOSS and 6/15 overall some recent
So, there's quantitative data of my experiences at recent events. Make of them what you will.
Oh, a bit more: 2 of the 3 assaults mentioned in the article happened this year. In the case of mine (the kiss), I was that person's second assault of the day/conference. The other was much more overtly sexual.