FWIW, I had a friend indicate that because (tenured?) teaching positions are such high demand, that the available candidates can be significantly high caliber. So that might have played into why the math professor was adversarial initially.
The area I've found the depress-to-impress used was usually in peer contexts and didn't have any teachable outcomes, unfortunately. They're regurgitating material that they have better familiarity with, but probably unable to ad-lib off their "beat path".
With the peers thing I just view it as we all have our pathologies, and some people just feel the need to be perceived as smart (usually some kind of insecurity). Sometimes it can just be too much though and you can get the feeling that you are walking on eggshells around them, perhaps not to trigger a judgement of you on their part.
I had an math professor (NOT the one I am referencing in another comment) that was ego-centric and would often respond to my incessant questioning with demoralizing (and sometimes flat out rude) responses. I just acted completely oblivious to the social faux pas and his avoidance/adversarial tendencies eventually turned into a much more productive relationship. I received the only A in the class (he publicly posted everyone's grades).