Is [insert community] toxic?

For any subculture or community - say, rationality, or raving, or crossfit, or social justice advocacy, or open source software, there are people who were once very devout members, but are now jaded haters. I think what's happening is that originally the community was so good for them that it hurt for them to consider that any part of it could be bad or toxic or harmful. Then, they were themselves hurt by one of the toxic elements, and there was some sort of sign flip, and suddenly it hurt for them to consider that there was anything good at all in the thing that did them harm.1 The reality is that any scene, being made up of flawed humans and flawed incentive structures, will have both good elements and toxic ones. The best communities will have relatively little toxicity while the worst communities will have a lot, but there's no scene where you can totally escape the risk of harm. The best one can do is to be aware of this, so you can protect yourself when you partake in this thing…