My former boss and I did an online carbon footprint test, and we were both doing great until we got to air travel. I was also annoyed with the lack of distinction between types of red meat, because while cows do contribute to greenhouse effect, kangaroo not so much. (It was a test on an Australian govt. site, although it's possible that they bought the test ready made.)

Often I think the problem with cheating on tests is the focus schools place on tests and test results. They make the stakes seem so high that even people who would probably do okay are tempted to cheat to avoid test taking panic.

One of the nice things about teaching at uni was that I was theoretically teaching adults and could treat them like adults. So my general advice was do revision in the week leading to the test, get a good night's sleep, and don't drink more coffee than usual because it can make you jittery and need to pee, neither of which are conducive to sitting in an exam room.