One of Dean's biggest assets is his "boots on the ground" operation and although the unions play a big part in that, the news this election is about the volunteers mobilized through the internet and Meetups. I know from experience that reports about the enthusiasm and dedication of these supporters has influenced many people to find out more about and commit to supporting Governor Dean.
So if one wanted to neutralize the impact of those stories and the volunteers...
...what better way than to impugn their motives, actions, and tactics?
Two "low-level" staffers in Iowa did the wrong thing, they were investigated, and they got fired. Immediately. That is what I expect of the Dean campaign.
Every other charge I've heard is innuendo, rumor, and old news. Until I hear definitively otherwise, I am going to assume that this is all oppo stuff. The news media is going to report it, and some folks may be influenced by it -- but I would encourage Dean supporters to recognize that these reports are almost certainly calculated attacks designed to counteract one of the significant advantages Dean has in this campaign.