I hear you. That has happened to me in China. When the pickings are good I am not a good teacher. When the pickings are slim boy how I stand-out!
I have been working at my present school for almost three years and they don't want me to leave. I doubt it's my teaching abilities, my good looks, or any of that. They give me an above average salary, allow me to work outside of school, pay for my apartment, utilities, and pay me the full market price of my plane ticket home every year.

I am getting harder and harder to replace. The first middle school across town has only had two foreign teachers in 10 years, and they are always looking. They just hired a 21 year old recent college grad. Funny but last year I had a conversation with a teacher from there who told me that her school did not need a foreign teacher. But in the true spirit of despotism the school administration just does what it wants. But she was pissed off at me for that. It's like the first wife taking it out on the concubine because she can't get at the husband. The first wife does all the chores(Chinese teachers) while the pretty concubine (foreign teachers) looks good to show off to the neighbors (the other schools).

Turnoi you work at the university level. You told us how the universities are looking for qualified area specialists with higher credentials, and these universities also have to compete against each other in China and the world. But the high schools, where I am at, also have to compete with other high schools.
So now Chinese universities want teachers with M.A.s and high schools those with B.A.s and TEFLs. This is one reason I think that San Migs can even afford to return to Britain and come back in the summer.