Sigh, holy moley...some crappy Yankee English testing company gave me only an ICAO level 5 but I don't write English like B737NG. Generally people who write English like that speak atrociously as well! I was PF to Madrid, my expat captain (a Latino )with level 6 English had to rescued from embarrassing himself with my " Konglish " saving the day
However after crossing the Pyrenees, he was the champion with the Spanish ATC!
So before you go on maligning Koreans about our ATC English prowess, be honest about some of your fellow expats who also have dodgy English proficiency certificates!