I don't think most folks like me reject the idea that good cops could exist, it's more that we're so aware of how many bad cops exist (at least in the US), it's one of those situations where good cops are run off the force (or worse, targeted and murdered before they can testify) or put up with so much bad behavior themselves that over time, they've become a bad cop, because they're not stopping other bad cops. Even if they're nice to citizens, if they're covering for crimes of their fellow cops, they're a bad cop. The fact that more cops aren't standing up against things like qualified immunity when it's painfully being abused or civil forfeiture when it's abused shows exactly how little they care for the public and how much they care for their right to abuse the public without recourse.

Unfortunately, that leaves most cops in the USA falling under the umbrella of ACAB.

Oh, and the whole 40% of cops self-reported as beating their spouses. On top of the whole "Killology" mess that trains them to be an occupying force in their own cities. It's really hard to make excuses for them at this point.