I've been watching the Three Stooges, the latest volume, which takes us up into 1952.
There's a couple episodes, maybe not on the latest volume, but certainly there's one episode there, in which the Stooges ingest some soap. Shemp thinks a box of soap is soup, because in the episode he can't read well.
The soup is served and it tastes a lot like soap. And one other thing gives evidence that it's soap. The Stooges have some very unnatural closeups and shots from the side belching out soap bubbles. Sometimes they come out one at a time, but on the side shots especially they come out as though there was a bubble machine on the side of their heads away from the camera and their mouths are simply open.
You can buy bubble mix for very cheap. I don't know if you could use it for washing dishes, but if you could you could save some money, because it's so cheap.
I wonder if any kid has ever drank a whole bunch of it. And what happens? It'd probably kill you if you drank a whole bottle, one of the big bottles.