I get it the other way around, NO ONE believes I'm Mexican. I go to Mexican stores and they speak to me in their broken down English, and are shocked when I respond in Spanish. I work @ a restaurant. Once while I was cleaning the bar there was a maintenance guy fixing the kegs/draft beer. He heard me talking to my co-workers in Spanish (they don't really speak English) and was like, "WOW! your Spanish is amazing!". I responded, "I'm actually Mexican", with a puzzled look he said, "WOW! your English is better than mine". Story of my life. I sometimes let them think I don't understand Spanish.. ex. when the Jehovah's witnesses came to my door, and asked if anyone spoke Spanish.. Nope not here lol.