I too am Sicillian and Irish, and I have a very ambiguous ethnicity. Folks of African decent think that I am mixed African and Caucasian, Native Hawaiian and Islanders think that I am either full-blooded or mixed Islander, I even get Indian, Middle Eastern, Native American, and once, Mongolian (not sure why; my eyes are olive shaped, but not *that* olive shaped). Once, a lady I met from Brazil got so excited to see me that she got halfway through a sentence in Portuguese before she saw the confused look on my face and stopped because I obviously did not understand her.
I think it is a tremendous compliment, since people always seem to think I am the same ethnicity they are, and so find me more approachable. Luckily, I am friendly, so once they find out I am not, they usually still stay and talk to me anyway.