Fashionable clothes, jewelry, flashy cars…. They are all items of conspicuous consumption that give their owners status on the street. Some groups, such as blacks and Hispanics, seem to spend more on such emblems of success than others. Or is that just a stereotype? Comedian Bill Cosby has long condemned his own black community for spending too much on flashy goods at the expense of children’s education. He has been roundly criticized by some and praised by others, but there hasn’t been much evidence to show whether his claims are true. Those who believe spending patterns vary among racial and ethnic groups typically invoke cultural differences, but there hasn’t been much solid evidence of that, either. “Blacks do spend more on these things — jewelry, clothing and cars — that have something to do with visibility,” says Wharton finance professor Nikolai Roussanov . “Is it just taste?…