"It is inappropriate and unfair to be angry with or mock someone who doesn't speak English as their first language and thus, occasionally makes an error or has to research a word or two or more while communicating. Such a person has taken the time to learn the language; the correct course of action is to help them if they desire help rather than moan at them for not being able to speak it properly. They want to learn! Can't ask for more than that."
I followed it up by saying that I was in no position to be a critic of a non-native speaker of English given that I only know a small amount of another language and all that knowledge comes from a computer game.