"Why would anyone think that?"

As I see it, one of the biggest problems in today's politics is that pundits and politicians alike tend to view their opponents as "evil" or "crazy". I put these terms in quotes because although they would never actually use these words, the meaning is there. Instead of treating opposing ideas as real concerns or honest beliefs by intelligent people, pundits often dismiss opponents without ever really examining their motivations.
Here is a recent example of that kind of thinking: "Democrats say Republicans staging town hall protests". In this case the Democrats quickly dismiss people's concerns and fears as merely "staged" by the villainous Republicans who only wish to hurt President Obama. Rather than acknowledge people's fears about health care, they have made it into a matter of spite, which is easy to ignore. This is merely one example, I could find just as many on the Republican side of things as well.
It is the same thinking that makes it easy to vilify individuals. Conservatives might assume that Clinton is a libidinous, immoral maniac without any motivation beyond himself. The more liberal might likewise assume that Bush is a power-hungry, lying imbecile who's only goal is to dominate America. I personally believe the motivations of each of these men is far more complex than any of us can understand, and have a few ideas on why I think they did what they did. By reducing these men to simplified caricatures, we can easily label and dismiss any action they make, even those we might otherwise agree with.
Does this mean that any opposing view is equally correct as yours? Not necessarily. For example, if I said it was 95 degrees out and you said it was 35, there are two possibilites: Either we are using differing measures (Farenheit and Celsius) or one of us is wrong. You should take a moment to examine their opinion to see if you need to make a change in yours.
The real issue is not that we all agree, because that will never happen and I don't think it should. What I would like to see is people able to hold their own opinions and beliefs and yet understand that another rational, intelligent person may have a differing opinion. If we can seek understanding with those people first, we may actually have a chance at convincing them. Without understanding why someone believes the way they do, you have no chance at actually engaging them in dialogue about their beliefs. It takes a lot of work to understand another person, but I think that's the way it should be.