I'm kind of the same way, except I don't really associate that behaviour with any colour/national origin. There are equal amounts worthless whites and worthless blacks. Sadly, at my school, all but two black kids that I know of are all as you describe. Also, I feel I need to say this, but they're not worthless because they're black, they're worthless people who happen to be black. Same as the worthless people who happen to be white.
One more thing: I refuse to use the word "race" as there is but one race, and that's human. I refuse to use the term "African-American" unless I'm referring to an African who is a citizen of America. I'm a humanist, and I campaign for equal rights for everyone. Your colour, gender, or sexual preference doesn't matter to me.