Well, as I have argued before, specifically w.r.t. Michael Moore, but also more generally with left polemical writing, leftists should be Caesar's wife when it comes to getting their facts straight.
This past weekend at my company's xmas party (oops, that is "end of the year employee appreciation gala", now), I was talking to my boss who has been reading Moore's latest book and was considering going to see Bowling for Columbine. He had once before asked me if I thought Moore was reliable when he was discussing the voter fraud in Florida. I noted that Moore was not always 100% spot-on with his command of the facts and offered to loan him Greg Palast's book on the topic.
Unfortunately, the guy started reading some of Moore's assertions about global warming. The guy has a PhD in Chemistry, is a practicing R&D scientist, subscribes to Science (and reads the damn thing), and is generally pretty well informed about scientific matters. He found things that were just plain wrong in Moore's presentation of the scientific facts about global warming. He now doesn't trust a word Moore says and will never pay any attention to him again. As he said to me: "Oh well, it was fun while it lasted", meaning it was fun reading someone entertaining whose politics were a little more interesting than he was accustomed to; but that now that he knows him to be a unrelaiable he won't reding him anymore.
Thanks Mike, I've spent the last 5 years gently nudging this guy to the left and getting him to read any politics at all.
-- no Onan