Darker tans can make you look thinner. With girls especially that does matter. Black hair is just eye-grabbing because it's not very natural (like the screaming reds or bottle blondes.) REAL tans can be tricky because they do age you really fast (darker skin is an aging thing, and the sun does make real wrinkles worse) but overall they make you look thing. It's like using the shimmer can make you look a little more toned.