I consider it extremely likely that such behaviour is more common at a geek tech conference, because alcohol-fuelled danced clubs, by their very nature, have lots of women present on roughly equal terms with the men. The small subset of men who are evil bastards to women when they get the chance will not generally act evil when there are lots of women around to spot it. When that situation does not obtain, they feel a lot more confident that they can do horrible things to the few women present and the men will simply not notice.
Alas, their reasoning appears to be correct.
(This appears to be analogous to the curious fact that teenage male scholastic achievement improves in mixed-sex schools just as teenage female scholastic achievement declines there. While the latter fact is attributable to the boys hardly ever letting the girls get a word in edgeways, the former appears to be because the boys tone down the more yobbish anti-intellectual edges of their teenage culture so as not to appear like yobs in front of the girls.)