No, there is clear evidence and the proliferation of conspiracy theories to promote specific political goals has been studied and documented by sociologists.

Yes, it's true, but uncomfortable for people in power to talk about, so that fits my definition above.

Other true things like slavery being bad, the reasons for the civil war, rich people getting away with terrible crimes while poor people were killed for minor infractions, Nazis targeting trade unions, kings being dictators, royal families often being foreign parasites, human races not actually existing and so on fall into this weird realm as well.