Can’t blame him, although I don’t know how you solve this prisoner’s dilemma in an Internet age. One site floats the rumor, word spreads via e-mail, a few other sites blog it, another dozen sites reason that it’s gaining currency as a meme and already Google-able so there’s no reason to ignore it, and it’s off to the races. The media gets wind of it, checks it out, maybe runs a public advisory story debunking it (e.g., “No evidence of Michelle Obama tape”), and finally puts a question to the candidate himself to give him a chance to blow it...