Lawyer needed, Legal advice wanted. Can I take a manufactured product and put my own label on it and sell for similar purpose?

Here is the situation. I found a product that would greatly help people. It is all over the place and marketed for what it can do. BUT consumers are always looking for a solution to a problem, this product would solve it but the company doesnt market it correctly. I could just purchase it, put my own label on it and sell it for twice the price easy.

1. People would be happy because their problem would be solved.

2. I would make a profit.

3. This other company would be selling more of their product through their distributors.

Is there some kind of law violating distribution profits or product infringement rights or some weird thing like that?

Example. Say Folgers coffee claims its made to wake you up. I find out it works 5 x better when served cold and only one cup. Is it legal for me to buy Foldgers, repackage with my own name and sell it as one cup cold coffee?

If it's not legal how could I go about making a profit on a situation like this. NOTE: this is not a discovery with coffee.

If I make a video with the product with my name people would flood my direction. If I show the manufacture they will just change how they show it.