I wish someone would do a study like this on e.g. cosmetics which claim to do miraculous things, but in reality rarely do anything at all. In fact I strongly suspect it all comes from the same giant vat of petroleum byproducts and the only difference is the fragrance, color, and emulsifiers.
If you just want to know the truth, not "prove" it "globally" in a "study", which essentially amounts to proving to the wolf that he is dangerous to the sheep, all you need to do is look at the ingredients list.
For extra credit, look the ingredients up and see how many of them have above-zero blue hazmat ratings.
That's not what I want though. I want an ex-industry insider with an axe to grind to tear them a new one, without mincing words, and with abundant evidence presented, similarly to how it's done in this article. It just blows my mind when some women who wouldn't eat non-organic food if their life depended on it turn around and rub petroleum byproducts into their faces every evening. Food colorings are "poison" but lipstick and hair dye are A-ok. :-)
That may not necessarily cause a significant change.
I believe that for a significant share of the cosmetics users, just doing some gym and adjusting nutrition would improve looks significantly more than cosmetics.
However, gym and diet change take effort, so it's "natural" to look for silver bullets. And looking for silver bullets is not about effects, it's about deluding oneself.
I agree on the theory that cosmetics do little or nothing. I was reading about somebody who claimed that the the general cosmetics effect can be achieved by home-made hydrating cream, and that over the counter cosmetic can't have significant effect, otherwise they would be dangerous (e.g., large amounts of certain vitamins). However, I can't find any reference.
