There's a lot of truth in your post, but were your 'minder' a Chinese lady teacher, or indeed the head of the English department were a Chinese lady, your way of being well regarded is much less certain to succeed. Chinese lady teachers will be very careful not to accept favours like yours. Firstly, because their husbands or boyfriends or colleagues may suspect there is romance in the air. Secondly, because they tend to be more ambitious than Chinese male teachers - so
they will not want others to say bad things about them accepting any kind of bribe behind their backs.
It's been my observation Chinese men tend to be easygoing and more inclined to repay kindness with kindness. Anyways, you seem to know what you're doing in order to continue teaching on mainland in spite of not being a good teacher. Though you didn't say your college was a state establishment, I would expect it to be so. A good piece of advice for you and your like is never ever work for private employers nor for those half public half private outfits, and you should be fine. And, I almost forgot, you'd better not complain about anything, that's the way to go. the Chinese dislike foreign wowsers.