I am an English teacher who has worked for two different EF schools since 2008.

My first port of call in China was Nanning. I'd had a telephone interview with the DoS of the school -- referred to as "the scottish man" in the original message -- and no alarms bells rang, which in and of itself was a positive sign given that I had rejected other jobs at the phone interview stage.

During the obligatory internet search I came across this thread. I was concerned but it seemed to me that the author was not putting forth any coherent arguments and had his own personal axe to grind. I'm also a bit of a snob and would be naturally suspicious of anyone who does not take the time to check a post for simple grammatical and spelling mistakes particularly when their authority is meant to be derived from the fact that they are an English teacher.
In any case, I emailed the DoS with very specific questions and he was courteous and replied to all of them to my satisfaction. I did end up working there and though the school had its problems (like ANY school in China does), I have very fond memories and I'm very appreciative of the time and energy the DoS spent in training and supporting all the staff.

I'd advise any potential employees to use common sense when trawling the internet and to take comments with a pinch (or heaps!) of salt. My experience at EF Nanning was in no way close to what the OP describes.