How Do I Know if a Study Is False?

A lot of researchers don't even publish their studies they don't like the results. This ends with the general public being misinformed about methods and drugs that work. Some laws have been put into place to prevent misrepresentation, but apparently this is not happening at all. For example, there are 25 studies proving a drug works and 25 that don't. It's more likely that 20 of the positive results have been published, and only one or two of the negative.