A racist holds the belief they are racially superior to others not of their own race. Sexual attraction is often stated as personal preference or how we make distinctions in our dealings with others. If you exclude an entire race of people in making those distinctions, stated as personal preference, the underlying belief of racial superiority comes into play or focus. I wouldn't worry about being called a racist if you arn't sexually atttracted to black men as a matter of personal preference. However, if the basis of your personal preferrence is rooted in a belief of racial superiority, you are indeed a racist.