The informant is 50 years old and from Riverside, California. She describes a saying that her mother, also from Riverside, frequently said: “You don’t know shit from Shineola.”
Shineola was a popular shoe polish manufactured in the United States in the 1940’s. Thus, it was very well known among American families, like a household brand. To say that someone couldn’t tell the difference between Shineola (a thick brown substance) and shit (also a thick brown substance) would be to question their judgement and intellect. When asked the context that this saying was used in, she replied that “It was always used negatively or condescendingly. Essentially, you were calling someone stupid. This could be a joking insult, or sometimes it was actually used to sound nasty to someone else.”
This phrase is interesting to me in that it is distinctly American by virtue of the brand that it includes. Other sayings call upon more generic objects, like an apple, tree, pencil, etc, but calling out Shineola makes this phrase only understandable to an audience that is aware of Shineola– in essence, an American audience.