For those people who are blogosphere junkies (blogoholics) (these are people who are analogous to those addicted to buying jewelry on the jewelry channel on TV whether they need it or not) their comments are in lots of cases “nasty, brutish, and short.” They do not add any meaningful insight to a controversial issue, only a diatribe against what ever the original writer or other blog commenters have said.
The sad thing about the above is that it reflects American society at large. Everything is easily politicized and issues are immediately polarized. Just reading the comments in response to blog editorials and the comments of other commenters is a scary thing to do. In fact parents should probably rate them as to whether they are appropriate for a PG-13 rating.
Sadly, it seems that people feel free to say anything they want, in any tone they want and on any issue they want; and hide behind an fake screen name. Many comments appear to be based on gut feelings, ignorance or ignore-ance (e.g., “I don’t care what the evidence is. To me the Earth really is flat,”) but not on a careful reading or even a basic knowledge of the issue being discussed. As a result, there are many reactive, sometimes hostile, sometimes even life-threatening comments stimulated by the serious blog editorials and comments. Once a blog comment that is inflammatory enters the stream of comments, it seems that a feeding frenzy occurs with increasingly hostile comments.
The image that comes to mind is mudwrestling, a free-for-all.
web.mit.edu/senior-house/www/history/roast/ Remove frame
There probably is no way to clean this up and it is something our society will have to live with. Much like in the late 1800s and early 1900s when street cleaners had to clean up the horse manure each day. 
But, it does show a dark side of the American public. More education won’t likely help; the commenters know what they are doing, they just may not know the deeper psychological reasons of why they are providing their comments as “nasty, brutish, and short.”