You need to set up some way of moderating the news story comments, because of the extremely low signal-to-noise ratio of the posts.
The "last straw" for me was the McDonald's/iTunes story comments... 20-30 posts saying "McD's sucks/BK rules" and then the horribly misinformed people saying other disgusting things... those comments need to be deleted.
This has become more and more of a problem. Even requiring people to register in the forums to post a comment hasn't helped. What will help is these people seeing their posts deleted on a REGULAR basis. Soon it won't be worth their while to do it anymore and they'll stop.
But, if nobody does anything, eventually the comments will be useless.