You shouldn't try and teach learners

Shouldn't is the key here, but it is China, and well, Chinese teachers seem to be ignorant of the hyperbole most Western FT's spew out...

Many Americans and English people speak good English, The Queen's English, although maybe with a slight accent across the pond and in Scotland.

I agree more or less with what you say, but please allow me to add that the vocabulary used by FT's should encompass few informal words, as defined by an advanced English learner's dictionary. One might put it in another way by saying that EFL should be taught using only English spoken by well-educated native speakers of English as opposed to that uttered by youths who left school in the West with little or no formal educational qualifications.
However, the Chinese regard Beijing Chinese as standard Chinese both in terms of pronunciation and vocabulary, more so the former. Accent snobbery looms large here among educated Chinese. Naturally, they try to apply the same approach they have to Chinese, to English. Yet they fail to realize that well-educated native speakers of English can understand one another easily irrespective of which Western country they have originated from, whereas in China there are huge local differences in local Chinese dialects and accents, which apply to the educated classes too, causing a general lack of oral comprehension among Chinese people living across the length and breadth of the country! Another problem is that the Chinese generally prefer to listen to English spoken beautifully, and if an FT doesn't or cannot speak so, he (or she) may be subject to a backlash. There are many naive and arrogant Chinese people among the educated classes who discriminate against foreigners on unreasonable grounds of pronunciation that is not perfect, So, beware!