As not a native english speaker,did you have the experience that..

There nothing wrong referring to the foreigner as foreigner since that is what you really him/her. its impolite staring to the person then talking about him/her language. There was one time, two ladies are talking about not knowing that I also speak their dialect. They really turned read when I asked them something in their dialect.

Well, one time, a foreigner came up to me and asked for directions on where should he go to ride a bus. I really didn't know what to answer but I talked to him like the usual way I talk and honestly told him that I don't know. I apologized and we both laughed at the matter. To think that we really didn't know each other in the first place and laugh in the middle of the first conversation which was just an inquiry for directions. Anyway, I haven't refered a foreigner as "foreigner" when they are present in the conversation. If we know the nationality and not his or her name, we'd refer them by the nationality instead.