John McCain is a honest dude. Sure, he flip-flops on stuff (see the bottom of this post), but he utters truths that a lot of other politicians wouldn't. A perfect example is his statement from December 2007: "The issue of economics is not something I've understood as well as I should." He's said similar things as well.
Problem is, uttering truths doesn't help you run for president. (Shocker, right? Is it a sign of a fundamental idealism or innocence that writing that statement genuinely upset me?) So now McCain is not just insisting that he does have economic expertise, he's actually denying that he said the statement in question. Think Progress has the depressing, not-very-honest details. Running for president makes messes of good men.