NYU's Jay Rosen explains the concept of "reverse verification" to Grist:

Verification is taking something that might be true, and trying to nail it down with facts. In reverse verification you take something that’s been nailed down and try to introduce doubt about it. “Was Obama born in the United States?” is the clearest example. The phenomenon of “verification in reverse” poses a special problem for journalists. On the one hand, they are supposed to report what people are saying. They are supposed to bring us the news of controversies, protests, disagreements. “Conflict makes news,” and all that. On the other hand, verification is their business. If they cannot support that, they cannot support themselves or their users. They are socially useless, in fact, if they cannot stand up for verification.