The disrespect shown by some students is appalling.
An acquaintance of mine was screamed at by an undergraduate who was unhappy with his grade. He used the F word and threatened him. I asked the professor what he did about it and he said nothing. If he reported it, nothing would have happened and the mud would have stuck on him, not the student.
Another acquaintance flunked a student who plagiarized a paper. (Passed in a paper identical to another student in the class.) Both flunked. One of the students made a formal complaint to the dean’s office and demanded the professor be fired.
Only a very few students are openly disrespectful. If they talk, its usually behind your back, almost never to your face. This was the first time it happened to me—kind of a wake up call. And you have to be very careful how you handle it.