Two ways.

If just one supervised flush and test had been recorded by someone reputable that would be fine. Or if a good number of people (say 100) had reported taking their stones to a laboratory and all had showed the presence of cholesterol and bilirubinates.
If I were selling something to expel gallstones; a book on flushing, or a product that was supposed to help to expel them, the first thing I would have done would be to have had the results from what I intended to sell tested. It is dishonest to say that, following these instructions, or taking this product will rid you of bile stones, unless you know that is true.
The fact that no-one selling these things appears to have made any attempt to prove their claims disgusts me. My conscience would not let me make money from selling something by making unproven claims. Many of the people who buy these books and remedies are clearly vulnerable, many are short of money. I find it immoral, that people can take such advantage. Tweet