Actually, in the best case, the criterion for taking things down is a few people silently and anonymously clicking the report button.

In the worst case, it's their NSFW algorithms identifying a nipple in the picture, with no regard for context.

We're still working out the kinks in the male vs. female nipple detection.

just btw it would not be anonymous.

If you are on facebook, you are logged into facebook, and they track every click.

It's anonymous in the same way that people complaining to the FCC about someone saying 'fuck' on television is.

Unlike the poster whose content is taken down, the reporters do not become part of public record. (I am not saying that they should.)