I know because my wife is Asian. And I have 4 grown kids who have dealt with that to varying degrees over the years. I've seen enough sideways glances and weird looks to last a lifetime. If you don't think that happens much, you're either naive or just don't care.
Regardless, I've made my point. You don't have to agree with it, but I've seen it frequently enough to know there are plenty of bigots out there.