Comparing corruption in one area of China vs. another is a bit like comparing a turd sandwich vs. a sh** burger and which one tastes less like cr*p. You haven't given clear examples of corruption in the public sector and while they may exist, they don't affect the immediate, personal livelihood of foreign teachers as much as the private educational sector. I think it's more important for expat teachers to know about the "schools" or schools that advertise a lot and will stop at nothing to spend money to deceive so they may exploit newbies.