Probably posted here before, but I always remember my mom telling me my teacher complained in conference that I told her she was wrong in class. My mom's response to her was: "Well, were you?" Likely it was in math.

I still wonder how many kids give up on math, because of mistakes a teacher makes on the board. A kid close to grasping muliplication and the teacher writes: 72 x 13 = 926 and a kid gives up forever because their hypothesis is blown out of the water.

But that's math, it gets much fuzzier in softer areas or if it is about pointing out fringe cases or the sort of extra data that muddles it for others. I will say the perfection line creeps me a bit. When all else fails, a correction phrased as a curious question can work.