One of my store bloggers asked me a question the other day, and therefore I just wanted to do a tiny explanation for everyone why things are as they are.
I make cosmetics (and mesh eyes and nail polish), and as a former skin designer I realize that making cosmetics entirely universal is very difficult and next to impossible unless making them for a specific skin. As a third party cosmetics designer, we have to hope that our products look fine on any number of skins (granted the skin one wears beneath the cosmetics is not full of dark cosmetics to begin with) and can cover lips, not mess with eyebrows, etc. The thing is, every designer of skins sets these differently, and therefore 100% camouflage is not possible always. Sometimes a cosmetic layer over an existing skin just does not work with that specific skin, and as a third party designer it can be a challenge.