I personally KNOW a lot of dumb rocks. It's VERY depressing.
There is a leftist in our neigborhood who is dumber than dirt. He used to be a VP for Shell Oil and worked overseas for most of his lucrative career; he registered as a Republican when he worked because he knew he'd be passed over for promotion if he admitted to being a liberal.
So, for most of his adult life he has had to hide his political persuasion. Now he lives in SC, solid Bush country, and gets regularly bashed whenever he opens his mouth. I love it.