Well, if it just boils down to "don't get caught and don't complain if caught"...

I don't know of any teachers who did complain once caught. It was in the news in each case that I saw, but more as a journalist running down the story rather than the teacher ringing up the local news network.
I brought up the point not as a "they should be allowed to complain" but rather "this should not be legal". I really don't care if people complain or not -- up to them.
But that's a far cry from I NEVAR BREAK MY WORD LEST I LOSE HONOR AND DISEMBOWEL MYSELF. Which is what some of this thread sounded like. (Not all from you, I might add.)