"Tricky" means "the other person is operating at a higher level than I am".

If you answer a question at a lower level than it was posed, you get marked down for failing to level up. If you answer at a higher level than the question was posed at, and the teacher fails to level up, you get marked down for what failing to level up felt like to the teacher -- misinterpreting the question, nitpicking, showing off, whatever. The task in an exam is to figure out what level each question is being asked at, and address it on the same level.