The point I was trying to make about liberal and conservative talking heads is that, I believe IMHO, the reason conservative talking heads prosper and liberal talking heads do not prosper is because conservatives are angrier and love to stew in their own juices publicly, so to speak. Liberals tend to want to rant in small groups, usually among fellow liberals (at the water cooler or the Unitarian church .) Conservatives like a bigger, more public venues for their rants.
I believe the recent success of Oberman and Maddow is due to things being so messed up by the Current Administration that the outrage has boiled over. Depending on the outcome of the election and whether things get better, I think the liberal talking heads may find thier audience will move on. Liberals listen to NPR not AM radio.
Another generalization I will throw out is that I believe that liberals are more likely to seek change locally, so are more involved in local rather than the national political agendas. Conservatives focus more on national issues (defense, terrorism, immigration, abortion, energy policy). It is harder for liberal talking heads to keep an audience when talking about community outreach programs, recycling and alternative transporation. It is easier to keep an audience when discussing "Big Ticket" items like right to life vs right to choose or terrorism.
Liberal talking heads find it harder to get steady listenership, because us liberals are busy tie-dying our shirts, going to the food co-op, adhering to our macro-biotics diets, attending Burning Man and taking the old lady to her Wiccan meeting.
Whew! Where would I find the time for AM radio?