I've also always used em-dashes, it's not a very reliable indicator. That style is a dead giveaway, though. Some of its comments seem to be written by a human, but several definitely aren't.

I've been spending less and less time here, the moderation is obviously overwhelmed and is losing the battle.

https://aphyr.com/posts/389-the-future-of-forums-is-lies-i-g...