The teacher I have in mind was saying things like Moon is a planet. It could be excused as geography was not her subject, although she advocated general education, she does not seem to have, a lot. Then, there were such things as proclaiming Aristoteles to be the greatest mind of Medieval. He didn't live in that age and there was completely different philosophy at that time.

I think this natural reaction - building a toxic barrier around themselves makes these people only bigger fools. Unfortunately, in my country, people at education are very badly paid, so this kind of people has chance to get there. And students have a little power to defend. Fortunately, only a fraction of people are like that.