An abnormally obsessive preoccupation or attachment; a fixation.
Actually the last definition is the only one with any utility in this conversation, yet it is still grossly inappropriate. Most of the people being described resemble
fixation not fetish. Fetish typically refers to inanimate objects (pantyhose, shoes, Elmo dolls) or parts of the body.
Many people probably have preferences of indeterminant etiology. Some are probably racist. Some are looking for novelty. Some are seeking a stereotype.
Fact of the matter is most people can get off regardless of ethnicity; if you can't you need a therapist.
I thought there were good looking Asians in America until I went to Asia; HK, China, Taiwan, Korea, Thailand, Malaysia, Vietnam, Singapore, Indonesia, and India. Everytime I changed venue I met at least one woman worth taking home to Mother.