All true. Too many people have this cartoon image of those they disagree with as being comic book villains, cackling with glee while plotting their next nefarious act. What this misses is the reality of motivated reasoning, by which people convince themselves of opinions of convenience--those which are flattering, consoling, or advantageous to themselves. They don't know they're lying. Even Hitler thought he was going to heaven, not in spite of what he did, but because of it.
And here's the killer question: how do you know that you're not doing the same thing? Serious philosophers and skeptics agonize over this all the time. There is actually a method to determine this, but that would take a book, not a posting.
George W. Bush was not an evil man. In most ways, he was exemplary--smart, considerate, funny, well read, disciplined. But he was a terrible president, grossly incompetent (and as much as I like Obama, he has not impressed me yet.) Bush's trust in Donald Rumsfeld, whom Gerald Ford called the worst person he had ever met in government, is a testimony to this. Rumsfeld really was a bad man, whose ambition trumped all other considerations, but in this regard he is actually quite rare.
Bad politicians are usually not bad people. They really do believe they are doing the right thing, but they came to believe this largely because they wanted to. The idea that this might be morally suspect is actually quite new; religion is a product of the same kind of reasoning, and witness how long it has been given a free pass. A new standard of ethics is being created, and it is still in its earliest stages. Don't be fooled by the cartoon version of reality.