When toothpastes claim to whiten teeth, and face creams promise to vanquish wrinkles, manufacturers usually boast that these declarations are backed by scientific studies. But if that research is bought and paid for by marketing dollars, then how trustworthy are these studies’ results? And just what does the phrase “clinically proven” on a label really mean?

Generally speaking, this scientific-sounding endorsement simply means that a product underwent some testing in a controlled setting. But when products are stamped with this authoritative label, “it’s easy to become a victim of the cosmetics industry’s advertising manipulations, exaggerations and deceptions,” says Paula Begoun, the founder of a watchdog website called CosmeticsCop.com.

Begoun says the quality of these essentially marketing-driven studies must be closely examined. Why? Because despite being subject to Food and Drug Administration guidelines, health and beauty products created for cosmetic use aren’t subject to the same strict rules and regulations that govern pharmaceutical products.

Legally, the Federal Food, Drug and Cosmetic Act defines cosmetics as “articles intended to be rubbed, poured, sprinkled or sprayed on, introduced into or otherwise applied to the human body…for cleansing, beautifying, promoting attractiveness or altering the appearance.” These articles include soaps, perfumes, lipsticks, deodorants, makeup, nail polish and skin and hair care preparations.

In many cases, companies make huge claims for these products based on a few small studies that don’t pass close scientific scrutiny. When it comes to cosmetics, “claims about how products benefit skin rarely have any proof of effectiveness,” Begoun says. What’s more, the results may be bogus because companies often pay researchers to get the results they want advertised. Translation: You might be paying for a dud product that’s actually harmful.

To investigate cosmetics companies’ claims, Begoun leads a team of researchers who comb through peer-reviewed research to let buyers know how effective consumer products really are. Then, she posts this information on her website.

Watchdog groups also exist for hair products and health supplements too. But consumers can also participate. Start by checking the ingredients on product labels and learn everything about them. (Ingredients usually appear in the order of greatest concentration.)

Just remember this: The next time a product claims to be “clinically proven” to give you younger-looking skin or a thinner waistline, it’s important to think long and hard before buying into what it is they’re selling you.