Oh lord that was hillariously funny, poor Air China guy you can hear people in the b.g. at the C90 laughing at him!
I've found (generally) the following are pretty safe to speak to : Japan, Singapore, Thai (can be a bit hit-and-miss) and any European carrier
Chinese controllers at PEK/PVG seem to speak pretty good English but then agian, they probably have to keep up appearences for the western airlines eh? lol