I have a BLACK co-worker, who is one of two women in the department, the other being Caucasian. A customer said "a girl helped me" and I asked which one. He very politely and gently says, "uh, the 'colored' one". I really, really wanted to go, "Hey pal, you can say black; in fact, it sounds better than 'colored'" but I just let it go. He was just trying to be nice, and he didn't know the proper term.
White customers do this all the time, and sometimes if I go, "was it the black girl?" they look at me which a shocked expression like I said "WAS IT THE NIGGER?".