Oh I love this thread ! My friends,who are English and spent a couple of years on motorbikes in South America, in the early 70s, Spanish speakers, were in Mexico, and were followed along a road there when they overheard one of the group following them, saying, 'Oh they are gringos'. My friend turned round and replied 'No soy gringa , soy Inglesa', and received an immediate apology and had a great night with them. So it's not just non-Spanish speakers but definitely U.S. citizens.