I judged again at the math circle contest, and some middle schoolers used social engineering, probably unconsciously, to try to force through their answer explanations.
The first one spent so long talking about her solution, which I wasn't sure made sense, that I gave up and waved her through. After she left, I realized that her explanation actually was wrong.
The second one answered a "is it possible to do X" question with "no" and her reason for it was that she tried a bunch of times and couldn't do X. We went back and forth, with me trying to land that you have to prove that you can't do X if that's your answer. I felt bad, so gave a hint that you can use graph theory to figure it out. Her reply was that she missed that class because she had a hockey game.
Interestingly, she later came back and said that it is possible to do X and showed how. The answer in the key is that you couldn't. Most likely, I bet we both misunderstood the question, but I gotta respect the daring, so I gave the points.
I found the whole thing mildly exhausting. I want to help out, but next time, I'm judging the elementary school teams.