Seriously. I was just reading through the comments on a number of YouTube videos related to the 2012 election, and at least 80% of them were just mindless insults and personal attacks void of any kind of intellectual rigor.
Then I clicked on some UK political videos and read the comments on those too, and while there was still a decent amount of idiocy, they were on the whole much more respectable and civil.
Most of those Youtube commenters probably aren't old enough to vote. The internet dumbs down what you see of American political debate because American internet usage these days is dominated by illiterate teenagers.