I don't think Romney is stupid. But he says remarkably stupid things.
“We have 250 years of coal, why in the heck wouldn’t we use it?” Romney said, speaking in front of hard-hat-wearing miners who roared in approval. “We’re going to take advantage of our energy resources to save your jobs, to create more jobs.” ...LA Times
Given the damage coal has done to individuals and to the environment, how could he say, much less believe, that statement? It's like saying cancer has been around for years so why spend time and money on eradicating it.
Visiting Appalachian coal country on Tuesday, Mitt Romney accused President Obama of “waging a war on coal..." ...LA Times
(Visiting Appalachian coal country on Tuesday, Mitt Romney accused President Obama of “waging a war on coal a killer...")
I guess where he was standing when he made those statements -- "the parking lot of the American Energy Corp. in eastern Ohio" -- indicates that he's not dumb but, yeah, terminally corrupt.