The media didn't smear Kerik. It was probably that Monday morning meeting he had with Corzine that made him change his mind. IMHO, he fared pretty well with the media, until after he declined the nomination.
If you think about it, Oliver North and Gordon Liddy are the media. They're basically media insiders. Either one could rise from the ashes. They should nominate one of them just for the heck of it. If they don't make it, the feeding frenzy would give the President time to find someone else.
the original issue about the nanny, was "outed" by Kerik himself. the subsequent smears of his affairs, his "mob" connections, his stock options, alleged gifts, etc - that's the smear job.