When I was researching potential cave instructors, I encountered an example in which people praising a certain instructor raved about his ability to curse you out articulately under water. I stayed away.Swearing underwater! That is intolerable, I would report it.
Tech instruction is by itself humiliating, and students are generally giving themselves all the bashing they need. They are trying to think their way through difficult situations, and having someone adding to their humiliation does not do one iota of good.