Agree about 'spectrum of intensity' - my first reaction to "I have no idea how dangerous your professors are" was "Well it's not like they carry shivs or anything."

what are the possible consequences of disrespecting them

I meant as a judgement, not an action. I actually find myself more conscientious about displaying signals of respect (addressing them as "Dr. Such-and-such", quietly paying attention, etc) to a professor I think is stupid. To use the language of "status" just-so stories, if I believe myself demonstrably more intelligent than someone, I only benefit by making them out to be high status - because that must mean I'm even higher status.