Ace of Spades makes a good point on this:
I was happy when dKos and their "conservative" partner Andrew Sullivan claimed McCain lied about his Vietnam captivity. McCain often seems to believe his own crap about civility and such in politics.
But when an opponent pisses him off, he goes for the jugular, in a "dirty" way. I don't think it's dirty. But he would normally call this sort of thing dirty himself. It becomes not-dirty when his opponents, or their supporters, do dirty stuff themselves.
Original video here, by the way.