Word choice is vital. I was once outed as a non-native english speaker because of a single word.

There's an old MMORPG that I used to play with friends as a kid. It has an item called copper shield. My friends and I didn't speak english at the time so we'd misspell and mispronounce the item as cooper shield. We had no idea what copper even meant, to us it was just the name of the shield. We all know what copper means now, but that didn't change our understanding of the shield.

A few years ago I decided to create a new account and play again for old time's sake. I joined a party and started talking to people. The second I said "cooper shield" I got a private message in my native language from a guy who learned it by playing the game with us. Because of that highly specific misspelling, he could tell not only that I was a foreigner but also which country I was from.