This problem is framed in a way that is subtly different from another way of looking at it that may offer different solutions. Looking at a given comment as a

This problem is framed in a way that is subtly different from another way of looking at it that may offer different solutions. Looking at a given comment as a "broken window" would seem to me to lend itself to specific treatments (i.e. a "flag" or "report" option), but you could also look at each comment as a contribution to the community that should be considered as a whole. I think if you treat every comment (exclusing illegal content or obvious spam/vandalism) as though it has value, even if that value is negative, it might lead to tools that highlight comments, demonstrating that they're unacceptable. HN (and now Engadget?) have shaded negative comments that are along the lines of what I'm thinking of.