I don't know where the balancing point is between "teachers are always incontrovertibly right" and "teachers are morons who don't know anything," but what I do know is that interactions like these are going to happen a lot more often when your cultural assumptions are basically at the latter point.
One of the first things my students learn about me is that I know enough about every subject under the sun to at least converse about it, and they also learn that I never stop looking things up, so they trust that I know what I'm talking about, but it usually requires a couple hard conversations.
