No, all Democrats and left-leaning commentators are right, always.
Currently, the lot of the major commentators on the left are of much better quality than those on the right. I don't believe this is inherent in one's political stand, I think it is just a coincidence of current events, in particular there's Republican money backing anti-science candidates and the Republicans joined with the Evangelicals in an unholy alliance.
The left wing idiots are more second tier: Mike Malloy, Randi Rhodes & Alex Jones come to mind. Robert F Kennedy Jr might be more mainstream, it's borderline.
On the right you have all the Religious nutjobs: Pat Robertson, Jerry Falwell (now deceased), John Hagee, James Dobson; you have Rush Limbaugh, Ann Coulter and Michael Savage. They get plenty of mainstream news exposure and make money courting ignorance. O'Reilly isn't stupid, but I do believe he demonstrates pathological lying and he's a bully. As I said, the latter qualities detract from any underlying intelligence he might otherwise have.
As for Cheney, Palin and Jindal, the left wing equivalents are weak, but not insane or ignorant. But let's not forget Michelle Bachmann. She as crazy as Katherine Harris.
Olbermann, Maddow, Ed Schultz, Stewart and Colbert are all intelligent and come across as intelligent regardless of what you think of their politics.