If you are looking for a products defects and ways to make it safer or more effective or more appealing to the public,
you have to survey or interview the people who have filed a complaint against the product or refuse to use your product, and take their concerns and experiences seriously.

Collecting these accounts are just one piece of the puzzle, but they are an important piece in seeing the whole picture.

It would be nice if independent non-biased scientists were provided the large amounts of money to fund a variety of types of studies that meets all scientific standards and look at things from all angles ... but until then we have to use our common sense based on what people's experiences are.