Thomas Tseng from The Melting Blog, posted this interesting story On July 19, 2004. It is another important aspect of the Latino culture that you need to be aware of.
Here is a short quotation, but you really must read the whole thing:
For years, scholars believed that colonial Mexicans actually lived according to this intricate system of racial castes. They mistook these paintings as depictions of social reality. But the categories enshrined in casta paintings never came close to reflecting the variety and dynamism of colonial race relations. And while the minority white European elite was obsessed with racial purity, most Mexican commoners were not.
But while widespread mixture made enforcement of a true caste system impossible, the notion of a racial hierarchy did nonetheless influence the nation's self-image. Today the relative absence of dark-skinned actors on Mexican television is a legacy of this tradition. Some Latin American-born advertising executives have imported this prejudice to the United States. Their advertisements routinely feature light-skinned models in campaigns designed to target a Latino population that is distinctly heterogeneous.