I know that apparently, some American travelers put Canadian flags on their luggage or carry on then claiming they’re from Canada (the dead giveaway on debunking this is their passport, since how can you be “Canadian” when you have US citizenship unless you’re a dual citizen in possession of both nationalities) since some of them have hatred towards the US or feel ashamed of the country due to its internal affairs.
When I lived in Japan, if I was out with my wife people would always speak to her (she was Japanese). My Japanese was reasonably good, and my wife said that there were no real issues with my grammar, vocabulary, or pronunciation, but still people didn’t understand me because I was a foreigner and they knew they couldn’t understand foreigners.