The spam filter on Reddit grabs a lot more things than you might think. It really sucks on the mod end because I'd have to click tools to even and one more click to even see if it there was anything there.

Perfectly reasonable discussions would get caught in it. I would then approve them, sticky them to the top for a few days so people could see them and write a post explaining.

How someone would do that in a high-volume sub, however, I don't know.