It's hard to determine 'rats' from the rat looking for some cheese.
The so-called 'blue-wall' is as historic as law enforcement itself. If you choose to work in a big city department you have to expect the politics you'll face from both the Union and the brass. If you put yourself in the game for a reason, don't even try to claim you 'want to help people' it's old and laughable, you want the pension and retirement benefits ...so be honest, and be honest you play along as long as you can until... like all desperate rats, you're forced to jump ship for one reason or another.
When it becomes too stressful, too dangerous or you feel you should've gotten that promotion or raise you suddenly reevaluate your career, it's often then, and only then you suddenly have morals.