Why is the rumor false?

I don't like false rumors. A false rumor is a wasted opportunity to give players an information key to a future lock. Too many false rumors create an unvirtuous pattern where the players doubt everything told to them, and stop listening to rumors all together--at which point you might as well not have them.That said, not all false rumors are created equal. A false rumor that is false for a good reason can be a worthwhile inclusion on a rumor table. When the players discover that it's false, they can learn new information by interrogating why it was false to begin with. This is an informational puzzle that can be fun. A bad false rumor: "Bree-yark is goblinese for 'We surrender.'" The reason this false rumor is bad is because it breaks down when you ask the question: Why would the NPC say this?Do they genuinely believe it? Why? They couldn't have heard the goblins saying it and thought they were surrendering, contextually. Did someone else tell them this bad piece of false information…