Old post, but wanted to comment because I just read this book and was thinking of writing a post on exactly the same topic! What are the chances? I wonder if I have anything to contribute - even though this article was written a year ago, I don't feel like there has been much of a shift in the rationality community overall.
An important thing to keep in mind is that cosmetics companies don't necessarily have the money that e.g. pharmaceutical companies do to push large-scale studies on their products, so lack of evidence usually means a study wasn't done, rather than a study was done and found inconclusive.
If you haven't heard of it before, the subreddit 'SkincareAddiction' has some great recommendations for what's evidence-based and what works.