A white person not wanting to date a black person because they are black, is racist. A white person not wanting to date a black person because they don't think that specific person attractive, is not racist. It is important not to conflate skin tone (level of melanin with race. If a white person has a preference for very pale skinned people (agnostic of race), then they wouldn't find very tanned white people attractive. Does that make them racist against other white people? No. Because race and melanin are not the same thing.