If an olive oil has gone bad, it’s rancid. Rancid is fat gone bad, and it’s okay, it happens.
What does rancid olive oil smell like? Crayons, old nuts or putty. Many olive oil brands are rancid, moldy or spoiled, sometimes before the bottle is ever opened.
Is rancid olive oil bad for you? You won’t get sick from eating rancid oil like you would from eating rotten meat, it’s just not pleasant and may ruin your dish. Rancid oil does not contain the healthy properties a good olive oil would, like the numerous antioxidants and vitamins.