While you are right thought i would get the GD opinion on it before putting it in the suggestion subthread because... no one goes there compared to them who use GD every day and who this effects. ;)
Well if you want my GD opinion, I don't think there needs to be any subthread to stop the shit posting. Whatever new subthread is made won't guarantee that GD or that new thread would clear up whatever shit posting is going on.
People respond to things they find interesting or entertaining so if people like Dude and Evil-Duck keep making threads it's because they are getting responses and people keep responding to them because they like doing so.
If it were such a huge problem, the community would have fixed it already because everyone already knows how to make someone go away.