I don't really have any horse in the race here, but since it is an interesting topic just want to add some more perspective
The tendency to dress up our appearance (for each gender), and for females specifically, wear make up, can also be positively related to self-esteem. That is, when women are confident they tend to match their appearance accordingly, while women low in self-esteem might have a tendency to 'hide' themselves more with less flashy clothes and makeup. Take as an example the stereotype of a nerdy girl, or a powerful businesswoman. This also holds true for men, that might start to pay more attention to the way they dress once their confidence goes up. In general, there is also an innate psychological tendency to match the way we interact with the world with our self image. For instance, in some cases people low in self-esteem have more problems accepting compliments from other, because they don't feel it is true (it doesn't match their reality, which makes it hard to accept). For those people, it is more likely they will underdress than overdress. Other people in turn might tend to rely on their self-esteem from others, which manifests itself in fishing for compliments. These people might be more likely to overdress in order to compensate.
So when it comes to self-esteem and makeup, it is more likely an interaction with other variables (for example, how outgoing someone is) that determines whether a girl with either low or high self-esteem will wear makeup, rather than a binary scale (makeup = low self esteem). Both can be true.
