There are many cases of a culture admiring rare traits of a foreign group. Ancient Greeks believed the blackness of Ethiopians was a sign of the gods' favor. Slavs, especially Russian women, will dye their hair red in an effort to mimic redheads of Western Europe. Indians historically favor fair skin due to the Aryan invasion but the trend has been revised in part by upper caste/class India integration with Europeans and Americans. Surveys have shown Mexicans are attracted to lighter skin. Finally, Americans historically have tried to copy the latest fashion trends from Europe.
While none of this is conclusive it does seem that beauty can be a rare foreign trait. Rariety, exoticness, and sign of social status all seem to combine into a formula. This makes beauty something one can never truely have unless they cheat like dye their hair or adopt foriegn dress... or at least that is what people tell themselves. Being happy with what one has, their own cultural traits, appears hard to do when somebody else has something so "beautiful."
There is a dark side though. Sometimes traits can be viewed as repulsive like black skin to "Enlightened-age" Europeans, black skin to Indians, and too-many American Indian features to mixed-blood Mexicans. Sadly racism is easily tied into what is beautiful and what is not.