For the purpose of this post, let's pretend that you belong to an atheist, humanist, or skeptic group of some sort in your local community. The group has roughly 20 members. Not all of them are equally active, but we'll assume that anywhere from 8-14 people show up at most of your meetings, events, etc.
There is one guy who attends regularly even though most of you wish he wouldn't. The nice way to describe him would be to say that he's socially awkward; however, that does not really capture the problem. He's not socially anxious or shy but awkward in the sense that he seems deficient in many of the basic social skills we take for granted. He rarely blinks, doesn't respect the personal space of others, and seems to have real difficulty reading social cues. He interrupts others, asks intrusive personal questions that make people uncomfortable, and rarely stays on topic. When he speaks during one of your meetings or events, an uncomfortable period of silence often follows because nobody knows how to respond.
Some of the women in your group describe him as "creepy" and say that he makes them feel uncomfortable. Although such descriptions would normally make us wonder about the possibility of harassment or other sexually inappropriate conduct, nobody has alleged any such behavior on his part. The worst thing any woman in your group has accused him of is inappropriate staring, and the men could all relate because he does that to them too. While many of the men in your group regard him as "harmless," some say that "creepy" is an appropriate description and note that he makes them feel uncomfortable too. Nobody in your group has any interest in being alone with this guy or in spending any more time with him than necessary. That's just the sort of vibe he puts out.
I realize this may be a stretch and that I'm just making up these numbers but suppose for a moment that there's one guy like this for roughly every 20 atheists who are involved in groups like this in their communities. The exact numbers don't really matter. It could be more like 1 in 10 or more like 1 in 80; I'm just picking 20 here because I had to pick something. The point is that this guy is far from unique. I've personally encountered enough people like him (and not all of them have been men) to suspect that 1 in 20-30 probably isn't too far off.
Now let's imagine that a large atheist/humanist/skeptic convention is held that attracts lots of people from these local groups. I have no idea what the attendance might be like at such a convention, and I'm sure it varies quite a bit. I'll assume that we're looking at several hundred to a couple thousand. And now you see where I'm going with this. Not only is the guy I described going to be at the convention, but there will be several others like him. Some will be less bothersome, and some will be more bothersome. And yes, it seems inevitable that some will be far more bothersome.
In the case of the guy I described, the women (and men) in his local group have had the opportunity to get used to his awkward style. This won't be true for anyone else at the convention. They are encountering him for the first time, and they cannot reasonably know whether he's "harmless" or whether the "creepy" vibe they get from his reflects something far worse. I think that's important to acknowledge. Nobody should be blamed for feeling uncomfortable around him.
I also think it is important to acknowledge that those who run into this guy (or others like him) at the convention are careful about generalizing to others. Sadly, it does not take more than one guy like this for someone to have a negative experience at a convention, and we know there will be far more than one. At the same time, we are still talking about a minority of those in attendance. It would be neither fair nor accurate to characterize everyone at the convention as creepy.
