I've always claimed that good cops are in the minority. I've had cops and ex cops agree.
A buddy of mine I used to work with in Boston left our company to become a Boston cop. We were having beers about a year later and he told me somewhat out of the blue that there's no such thing as a cop that isn't corrupt. I asked if that applied to him as well, to which he just looked right at me, cocked his eyebrow, picked up his beer and finished it.