In the past, expat foreign teachers working in China without a "Z" visa (work visa) were usually detained for a day, fined 1000rmb and given a warning along with 30 days to get the right visa. In July of 2013 all of that became ancient history. Now the warnings have been replaced with deportations and 3 year re-entry bans.
In June the following stats were published for 2014 which is only half over...!
"To date, 1,637 expats have been expelled from China in 2014, and 1,237 of these have been foreign teachers. 1,015 were found working on L, F, and X visas, fined an average of 10,000 rmb and deported with three year re-entry bans.
Willy