Actually, I think the vast majority of people on both sides are civil and respectful of their opponents. Otherwise, why is there such support for the "dream ticket" scenario of Obama/Clinton or Clinton/Obama? (Not that such a scenario would ever happen--Obama would not want to be fighting for second place with Bill, nor would he want Hillary's negatives if he were the nominee.) Yes, there is a noisy, nasty minority on both sides who spew venom, but they are a minority and I think most voters are aware of that.

Bear in mind also that venom is vastly magnified on the Internet, and nowhere more than in forums dedicated to political discussion. What we online political junkies see isn't necessarily what most people experience.