How to Tell a Rumor from the Truth
Think about whether you're dealing with a piece of information or just hearsay. For example, if someone says, "Barbara saw the boss and his secretary leaving the Hilton," that's a concrete detail you can verify, but "Barbara heard the boss is having an affair" is likely salacious gossip. It may be a subtle difference, but it matters. That said, you can never know definitively unless you're an eyewitness. So my rule of thumb is: Don't believe until there's a reason to.
—Ana Marie Cox, columnist for the Guardian and founder of the political gossip blog Wonkette