Anna Maria Barry-Jester, writing at FiveThirtyEight, on all the rancid olive oil we probably use:

“We call the U.S. the world’s dumping ground for rancid and defective olive oil. We don’t know the difference,” said Sue Langstaff, a sensory scientist who consults for the beer, wine and olive oil industries, among others. Studies have shown that even frequent olive oil consumers in the U.S. don’t know what the extra virgin or cold pressed designations mean, let alone have the ability to taste the difference. And in blind taste tests, consumers often prefer lower-quality olive oils.