As typical of somebody posting a throwaway comment to an online forum, I'm not sure that you've taken everything into account when you make such a broad statement.
That is, we're hearing about bad cops who aren't being stopped by good ones. A lot. "Well, the good ones are out there!"; they're either ineffective, or effective, in which case the number of bad cops is even higher than we hear about. Neither of those is particularly placating.
Good police exist, and will continue to exist, despite civilian hostility and shifting definitions of what it means to be a "good cop". I'll never claim that no police are bad, or that there aren't many bad police, but I know that I'll never envy the good ones as long as the people filling this comment page comprise the majority of our population.
I'm saying, we hear about X bad cops.
There may indeed by Y good cops. I am not making any claim about the existence or non-existence of Y good cops (in fact, I've interacted with good cops, so if I was to make any claim at all, it's simply that they exist, and the effects they have on bad cops are unknown).
These Y good cops are either doing nothing to stop bad cops (and thus are ineffective at stopping bad cops; this may be simply because they are in different departments, and/or unaware of it if it's happening within the same one, and/or they may be powerless to stop it, etc etc), or they are effective at stopping Z bad cops (for a total number of X + Z bad cops, since X are still not being stopped).
Either of these situations is terrible, because either the good cops are not stopping bad cops from being bad, or they are, but there are enough bad cops that the good cops are unable to stop them all (and thus the numbers of bad cops are even higher than we hear about).
I'm not sure how else I can put that for you.
I agree that our current situation is sub-optimal. I don't remember ever arguing otherwise.