Those on the right - no matter what their nationality or race - who dare to share conservative values are dismissed as stupid, ignorant, mean-spirited, war-mongering, selfish, greedy, hateful, nativist, racist, sexist, homophobic, xenophobic, Islamophobic, bigoted, intolerant, fascist, misogynistic and hypocritical.
Those on the left are clear to let you know that they are none of these. The left views themselves as better, kinder, smarter and more moral than those on the right. And since they are, there is no need to talk to, be in the same room with or vote for such mean-spirited humans.
The left cannot ascribe good intentions to the right. If they do, then the ideas of the right must be seriously considered. Instead of dismissing Herman Cain as stupid, inauthentic, or mentally inferior, the left would have to explain how his positive attitude about America allowed him to transcend any lingering racism and be successful. They would have to explain what it is about leftist ideology that sees racism everywhere (here, here, here) while the right acknowledges pockets of racism while projecting the hopeful message that it can be overcome.
If conservatives are just racist bigots the discussion is over. If they are good people with different ideas, the ideas have to be addressed.