Can racial preference be racist, yes. Is all racial preference racist, nope. Just like gender preference, eye color preference, hair color preference, or any other preference is not about the other person or judging them. It is instead recognizing the stuff you find attractive. That might be a 300 lb mustached Latino woman who is a dominant in BDSM, or a 100 lb white woman with short hair who prefers vanilla sex. The person attracted to the 1st is likely not attracted to the 2nd and similarly the other way is typically true.