I was open to an innocent interpretation, but I thought that the most likekly interpretation was thoughtlessness betraying a tiny bit of subconscious prejudice.

My focus was not, however, on the USA or on the white/black divide in particular. It was just one of many examples. Other instances:
We have a verb in German, if I translate it verbatim, it says 'to turk' and it means to cheat. I have used it all my life unthinkingly until a student told me I better shouldn't (we have a lot of students of Turkish descent).
Recently, a Mudcatter wanting to express his dislike of the leader of the British BNP called him "Herr Griffin". I guess he even didn't think for a second that German Mudcatters could find the use of the word 'Herr' to express extreme dislike of a person and/or to allude to right radical and fascist positions insulting.

Wolfgang