Kerry's campaigning is so low blow, so forthrightly slimy, that I almost think the Bush and he deserve each other. In addition to all the trash talk half-truths about Dean's record, th Dean campaign apparently has a video tape of a voter veing push polled during the runup to the Iowa caucus by someone favoring Kerry. And Dean's not his only target, there is a rather nasty flier regarding Clark in this post, which, though I suppose it is mostly true, is very harsh and is said to have come from Kerry's camp.
He's apparently not above breaking campaign finance laws, or at least winking and their being bent, either. A very trusted source sent a flier to me which purportedly came from a Kerry staffer or volunteer at a Clark appearance in Arizona. This scan of the flier has no attribution or 'paid for' on it, I can only assume that it is accurate and undoctored.