To be honest, my "experience" is highly unscientifically based on speaking a little bit of German (or eavesdropping) with a total of roughly three dozen Germans through a couple hostel-hopping trips around China before I got tied down to the wife. The primary conclusion was reached when I couldn't understand most of them very well at all (and was often left wondering if they were actually speaking German in the first place), but I was pleasantly relieved when I chatted with a couple Hamburgers who met by chance in Chengdu one summer.
There was also absinthe that night, along with an Australian guy taking the wheel of our taxi when the driver stopped to ask for directions, and another Aussie peeing for at least a minute and a half in the middle of the road with constant traffic whizzing by (pun not really intended, but recognized), so any reliability you might have been willing to concede to my experience probably goes out the window with that confession.