I have never heard of this one before: The Hot Potato Test for determining if your olive oil is fresh and of good quality.
This tip comes from Gaea, a Greek manufacturer of olive oils.
"Boil or bake a potato and directly after taking it out of the pot or oven, pour the extra virgin olive oil on top and smell. A good quality extra virgin olive oil will smell pleasant, aromas like freshly mown grass, olive fruits and olive leaves. A poor quality olive oil will release a heavy unpleasant smell when poured on a baked potato."
Interesting tip I may have to try someday.