Want to know how deeply embedded the "popular idea" of slavery is?

I listen to the Skeptiko podcast with Alex Tsakiris. He had on a guest who mentioned that slavery in the US was not at all common, with perhaps 5% owning slaves. Alex disagreed.

So did Alex ask him for his source, or quote a figure from his own sources, or pause the interview to do his own quick research? Nope, he kicked the guy off the show. Nothing at all like that had ever happened in over 500 episodes. Oh, and he has never mentioned it since, so I would conclude he never did any research on it himself after that.

Alex is liberal-leaning but not an NPC either, as far as I can tell. But the programming runs very deep, right down to the bone.