The best illustrations of this, one of the most bizarre and sometimes amusing forces of utterance, often come in student evaluations. And even more frequently the comments that damn by oh-so-faintly-praising sum up in almost soundbite form how the class went, and so they are frequently quite revealing about multiple parties involved. Here's the best example from the most recent batch of evals:
"Didn't let an unenthusiastic class change overall trajectory of course"
And this under instructor strengths, people.
Here are a couple of readings, and oh do I welcome more in the comments:
optimistic: The class wasn't interested in obviously interesting material, but she persevered, remained upbeat even. She really sticks to her theoretical and pedagogical guns.
pessimistic: This woman is boring AND stubborn.