主题：【原创】2007美国网球公开赛之花絮抓拍-莎拉波娃 -- 游魂

Skin quality should not be judged by whether it ‘looks dirty’ or not. Your criterion is biased. From our aesthetic perspective black or dark skin color is perceived as 'dirty'. But our aesthetic perspective is deeply rooted in our culture, therefore it's biased.

A more objective and fair set of criteria should have no place for skin color. Normally the skin quality is judged by the degree to which the skin has a silky feel and a gleaming look, the degree to which the skin can stand harsh weather, etc.

With this set of criteria, on average, black people's skin has the highest quality among the three major groups of people.