Uh... yeah? Though how this usually works isn't actually back table or under table deals. If you search enough you can find a study or group of scientists who will find a positive or negative result in anything. Repeat any study enough, there is some percentage chance of it going the way you wanted. This is in part why people have variously argued p < 0.05 is not good enough. This XKCD comic perfectly illustrates the problem.

So what happens is, companies like coca-cola can just dredge up any group of scientists to keep studying something with enough different designs, and then only publish or support publishing null results. That is, results in their favor. Or ways of looking at a problem that is in their favor. Issue is that people who are not obese and drink soda tend to remain not obese, for example, because obesity is more like a social disease. The more acceptable you think it is to be obese, the less care you take in keeping your weight in check. For the curious: Paying people to lose weight actually is the #1 most effective means to get people to lose weight. What keeps it off is sticking to thin friends.