I think this has to do with the hierarchy within blacks and browns. I think "shadism" is a reference to how blacks treat lighter blacks and browns worse because they look whiter. This would make sense within the reference to makeup because makeup will change your shade. This is how they blame White people for racism when there are no White people around being racist. I'm not really sure about lookism. Maybe it refers to how many looks you get when you wear makeup and therefore look more attractive than when you don't. That's my best guess.