None are, until we catch them in the act. It's what doesn't happen to those when caught that pisses most of US off.
My 40+ year of experience dealing with police departments from forces of three to thousands has taught me that 85-90% of police officers are honest, conscientious, brave men and women that do their level best to protect their citizens from the scum that surround them.
For the most part their personal well being is low on the list of priorities and although tend to give the benefit of the doubt to their fellow officers but WOULD NOT cover for them if they reasonably suspected malfeasance.
I find it infuriating that vacuous, uninformed, mindless loud mouths would state or imply the opposite as if it were fact.
Actually it's what DOES happen. By this I mean the active and deliberate criminal actions that are used to excuse and enable a culture of out of control cops.
Does Internal Affairs find wrong doing in even so much as 0.1% of the cases? Does anyone know the actual statistic?