Obviously this applies to white people more so, probably because of their self righteousness and belief that all etnic minorities are low lives.
Technically, thats also racism.
But anyway, I dont think the majority of people really judge that much based on race, if someone isnt attracted to someone, its not just usually their race, it can be anything. Some people simply dont find some races attractive, that just happens, the same is true with body types/sense of humour etc.
I have also not known anyone I know to reject anyone simply because they thought they were an immigrant, I have known people to reject people who were cocky, rude or what they considered 'ugly', but not race.