As a former liberal, I have some insight on this topic. I can tell you that majority of liberals want to sound intellectual on every single subject even if they have no idea what they are talking about. And chances are, if they are talking with other liberals (i.e. inside the bubble), the other liberals have no idea about the subject either, so everyone nods in smug agreement.
When conservatives (or other knowledgeable people) confront liberals on the facts, the liberal will go into verbal gymnastics to defend their original (usually absurd) position. It can be really fun to watch (see early posts on this site)..but it quickly becomes tiresome. Why? Because you quickly learn that liberals are consistently wrong about nearly everything but they want to defend their stupid positions until their muscles can no longer move their jaws.
This article is a great summary but it could have hit harder..
Why are liberals so condescending?
By Gerard Alexander
Every political community includes some members who insist that their side has all the answers and that their adversaries are idiots. But American liberals, to a degree far surpassing conservatives, appear committed to the proposition that their views are correct, self-evident, and based on fact and reason, while conservative positions are not just wrong but illegitimate, ideological and unworthy of serious consideration. Indeed, all the appeals to bipartisanship notwithstanding, President Obama and other leading liberal voices have joined in a chorus of intellectual condescension.
It's an odd time for liberals to feel smug. But even with Democratic fortunes on the wane, leading liberals insist that they have almost nothing to learn from conservatives. Many Democrats describe their troubles simply as a PR challenge, a combination of conservative misinformation -- as when Obama charges that critics of health-care reform are peddling fake fears of a "Bolshevik plot" -- and the country's failure to grasp great liberal accomplishments. "We were so busy just getting stuff done . . . that I think we lost some of that sense of speaking directly to the American people about what their core values are," the president told ABC's George Stephanopoulos in a recent interview. The benighted public is either uncomprehending or deliberately misinformed (by conservatives).
This condescension is part of a liberal tradition that for generations has impoverished American debates over the economy, society and the functions of government -- and threatens to do so again today, when dialogue would be more valuable than ever.
http://www.washingtonpost.com/wp-dyn/content/article/2010/02/04/AR2010020403698.html