Rancid oil is smells bad - you can even smell it in nuts and seeds that have been on the shelf too long - I always smell nuts and seeds before I buy them. Anything that contains any oils at all should be checked first for it. Sometimes they have bulk items on sale that have been on the shelves too long and you can tell because it has that rancid smell. Always check it. I always put nuts and seeds in the refrigerator.
Recently I read an article in, I believe it was the New Yorker, about the corrupt olive oil industry. Apparently there is a lot of bogus oil on the market that has been colored and flavored to resemble olive oil. It's definitely something to think about and be aware of.
I would definitely take anything that was not perfect back to the market for a refund.