I am from West Virginia. Growing up in the 70's we always called anybody of Hispanic descent a Mexican. I t was not meant to be derogatory that is just what we thought you called them. Then I moved to Florida and I quickly learned that most Hispanic people aren't Mexicans. Mexico is a country, not a person. There are Dominican, Haitians, Cubans and so on and so on.
I also quickly learned that it is an insult to refer to someone who is not Mexican as Mexican. I didn't have a problem with it. I changed when I knew better.
I was living in an apartment complex once and had some very good friends named Maria and People. Maria was Caucasian and lived with People who was one of the Cuban boat people who came over in 1980, I think. They were very nice and Maria was the interpreter when People and I had trouble communicating because of language but we were generally able to get by on our own.
My stepdaughter, Katie, came down to Florida to visit when she was 18 years old. Maria and People had a little get together in her honor. It was very nice and we were having lots of fun when Katie referred to someone as Mexican. She did not mean it in a bad way, she just didn't know any better. Just as I hadn't.
The men were a little tipsy as we were at a party and immediately an uproar started. (to put it mildly) Everyone started yelling in Spanish and gesturing frantically moving at Katie as one. She was looking around completely befuddled at whatever she had said to start such a panic as Maria and I moved in front of her partly to protect her (although I don't think she was in actual physical danger) and party to stop her from saying anything to potentially worsen the situation since she didn't have a clue what was wrong.
I shushed her as I started to explain. (much like what is in the first paragraph) and Maria was urgently translating everything I was saying as People and the others listened. When they took a second to look at Katie they could see the distress and puzzlement on her face. People immediately moved to calm the other revelers because he knew he was dealing with a child who didn't know better as I explained to Katie exactly what was wrong.
She was upset that she had upset everyone because that wasn't her intention and started to apologize profusely. People started to assure her that no apologies were necessary while kicking his party into full swing again.
all's well that ends well.