Why do intelligent design theorists screw about with facts like evolution?

It's very simple actually. A lot of people have swallowed the tripe that belief in a god and evolutionary theory cannot coexist. That's actually not true. Many Christian people are perfectly fine with evolutionary theory. What the problem is are the people who take Genesis literally. The ones who believe that somewhere back in time, God plunked Adam and Eve down in the Garden of Eden. This view is irreconcilable with evolutionary theory. Evolution disproves the biblical account, if you take it literally, which would then disprove the religion. See where the problem is? So if god can't be wrong, then the theory must be. So find whatever problems you can with it and run blindly. It's what happens every single time religion finds itself proven wrong and cannot adapt its world view.