Even a broken clock is right twice a day.
I think they make a great contribution to the forums. What we need is a dislike button and for more people to use the like button in the deals board, so threads can be deleted easier if it's not good. And maybe another board for when deals die.
But in general I think your comment is way off and the amount of good deals produced by DDF has gone up exponentially since they started contributing.
Sure some posts can use a bit more discretion and looking into, but that's where a thumbs down and thumbs up feature people actually used would be helpful. No need to throw the baby out with the bath water.