It's like F1 tyres at the start of 2012: Quick-degrading? Perhaps good.
Exploding somewhere in Spain and England? Not good.(Which is to say that a score of "-2" should not be enough to hide a comment, "-10" or "-7" would be a bit more sane.)
Honestly I don't think a comment should be hidden at all. The worst thing that should happen to it is getting a bright red/maroon background with the text being changed to white.
