Are we more likely to trust products that have the phrase "clinically proven" on the label? That's certainly what manufacturers want us to think. After all, if a product is "clinically proven," it must be more effective than a product without such a claim, right?
As it turns out, the answer is a little more murky. To be able to put the phrase "clinically proven" on an over-the-counter product, the manufacturer does, indeed, have to had tested the product in an experimental setting. However, the stringency and legitimacy of these tests are not well-regulated. The product could have been tested in anywhere from one person to a million people. And the tests could be poorly designed and biased, since they're usually conducted by the manufacturer.
So if you encounter a product that advertises "clinical proven to...," be skeptical about its claims. As the old saying goes, if something sounds too good to be true, it probably is.