Not sure who made up that statement, but I learned it in basic training from my Sergeant Darnell, who was our company NCO. The reason I was not familiar with it was the word Shinola, which happened to be a shoe polish product. My experience was only with shoe polish named Kiwi, Griffin and Esquire. Don’t believe that Shinola was sold where I lived.
The alliteration of the statement made it a popular form of put down in the army. Your instructors would use it when someone got out of line by correcting an NCO or an office. “You don’t know shit from Shinola, cruit.” Cruit was short for recruit or a way of not pronouncing you name which was emblazoned on your fatigues or field jacket.
The saying grew more popular in different parts of the country as pt. and movies made great use of it. I have not seen it used with relation to our political process recently. I believe that it should be used more often for that particular group of people. It came to me in a flash when a political type was praising the soldiers of the Great Generation who fought on the beaches in Normandy and were invited to the new memorial in Washington. The politician said that he was proud to be there with a group of 90 year olds who had volunteered to serve their country in World War II. I guess this guy has never heard of the draft.
There are some other notables around the country. How about the U.S. Senator from Wisconsin who is running for his second term in the senate and has not mentioned in his public discourse that he is already a senator. He claims that he is an outsider and will go to Washington to fix things. I guess he thinks that his constituents “Don’t know shit from shinola.”
How about the many candidates for federal public office who promise that singlehandedly will get rid of this or that and will take our country forward where it has never been before. I believe that there are three branches of government and that doing any of those things will require the cooperation of at least two of those branches.