The reason ACAB is because a good cop exists in a superposition between resigned and murdered tragically killed in the line of duty, and the act of reporting a bad cop collapses the waveform.

I was of this conviction until Amsterdam riot cops hunted down protestors like animals and beat them relentlessly, without reason, after they were released from custody, and not a single other cop denounced it.

(Here's a short compilation of videos taken while it happened, a journalistic video piece and a news article)

Good cops should prevent bad cops from existing.

There are no good cops.

You forgot to add "...for a very short time per individual" at the end