apparently if I find a poorly done study or two, and ignore hundreds of others, I could get a big payout via our court system.
Please don't spew nonsense like this about our court system. Is the court system infallible? No. But the plaintiff in this case had to overcome significant legal hurdles in order to win this award:
A doctor had to testify that the Roundup caused his cancer "with a reasonable degree of medical certainty." That is a high burden, and while there are "for profit" doctor experts out there, most of those doctors are easily impeached during cross examination.
Given your hypothetical, the doctor would have to convince a jury of your peers to rely upon "a poorly done study or two, and ignore hundreds of others."
And they would have to do so while going up against a large corporation's very good and very well-funded lawyers who routinely defend against cases such as this.