I had to laugh at the suggestions that anyone being harassed report it, the last few cons I went to were quite chaotic, staffed by often teenage volunteers who were up to their eyeballs in trying to keep people in lines etc.. I can't even imagine who I would report such a thing to. I would not have been able to find anyone.
What kind of conventions are you going to? At the fan-run conventions I attend and help to run, it's fairly easy to find a committee member. At the very least, there should be an Info Desk where, if there isn't a committee member on duty, they should be able to summon one fairly quickly. (Some conventions combine the Info Desk function with Registration, so if they have no Info Desk, that would be the next place I would try.)
At the cons I work on, it's even easier - anyone wearing a headset or a T-shirt with the word "Concom" on the back can help.
And most cons have a Security department. It's only the big for-profit cons, in my experience, that hire outside security whose only job is to make sure that you don't come in without a badge.
(Yes, this is all fairly obvious when you've been attending or working on conventions as long as I have - which is about 25 years. So if the above comes across as condescending, think of it as a public service announcement for people who are fairly new to fandom.)
Yeah, reporting it is easier said than done, and really, unless the folks running the con get a lot of reports about one particular person, most offenders are going to be ignored.
Not necessarily.
I won't name any names, but I have a friend who is fairly well-known in fandom (which doesn't narrow it down at all) who, at a convention a couple of years ago, was accused of sexual harrassment. Anyone who knows him - and as I said, that's a lot of people - wouldn't think him capable of such a thing.
Not only is he well-known in fandom, he was well-known at this particular convention - he'd been attending for years, and had several friends on the committee.
The convention's response was to ban him for life.
Yes, there was some blowback - as I said, the described behaviour was viewed as being out of character for him, but that didn't stop this particular convention from acting on the complaint. And as far as I know, this was the first time he'd been accused of harrassment, so it's not like he had a reputation.
There has actually been a lot of conversation about this sort of thing on an email list I belong to for people who run conventions, and as a community, we're doing our best to bring our policies up to snuff. The fact that most conventions didn't have a formal policy on the subject, in my view, only goes to show that most fans are reasonably well-behaved and implementing formal sexual harrassment policies wasn't thought to be necessary.
Though, again, at the big for-profit shows, it might be harder to get anything done about incidents like this because, frankly, it seems to me like they don't care about the community aspect of fandom the way the fan-run conventions do.