What about these 'pretend schools' who farm you out to middle schools; should one work for one? I would say yes, but just want to know what you think?

I'd say be wary. Do your homework first. The Beijing-based ones tend to be the greediest, not surprising, really.
I've butted in here coz Turnoi is an academic, and has therefore had little involvement with the seedier side of EFL in China, unlike the likes of you and I, ourselves being non-academics.
You needn't thank me for my intervention - I'm more than happy to be of service.
PS, I'm sure Turnoi will vouch for me in this regard if you happen to distrust my good words, won't you Turnoi?