I've seen news articles that Drudge has linked to that have Facebook comments where people use their real name. This may surprise some people but -- they're not usually very polite!

And every evil subreddit I've come across was the result of "effective moderation", they moderated everyone who isn't evil.

Lax moderation, the good ole downvote button & find some way to discourage circle jerks, that's probably all you can do. You're never going to make the Internet not be a sewer though.