They've stopped caring tooIn one of my classes today, a girl answered a question with straight jibberish. Not words, just a collection of "um, well, yeah, blah" or something like that. But she did it with convincing intonation, as if she were constructing a real sentence.
The professor looked at her for a minute, and then said "yeah, that's right..." and continued with the lecture. Proof positive that just as you aren't paying attention to your professors, they aren't paying attention to you.