Why does it matter? Does someone have to smash their foot with a sledge hammer to prove to themselves that it will hurt? Or is evidence and common sense enough to tell them that they do not have to smash their foot to know that it is going to hurt?
The evidence is overwhelming that what people are passing are not real gallstones. Even when people have sent these "stones" to a lab for testing it was confirmed that they WERE NOT real gallstones. How much evidence do people need before they finally start realizing that these flushes are quackery?