When I was a student at UC Berkeley in the 80s, I worked on campus at one of the faculty clubs that also acted as a hotel hosting visiting academics. Late one night I was expecting two arrivals, a Mr. Takemoto and a Mr. Kim. One of the two gentlemen arrived and I tentatively asked, Mr. Takemoto? He was silent for a few seconds, started gritting his teeth and turning red, then said in an angry voice said "DO I LOOK JAPANESE TO YOU!?!" I was a naive kid still unaware of how Korea suffered under the Japanese during WWII. I learned my lesson and never assumed anyone's nationality/ethnicity again.