I've been around and done the job long enough now to have a qualified opinion on it. I will say this, however, good officers screw up too. My Sergeant is someone whose opinion I take seriously, as he's been on the job and in the street 16 years longer than I have. About 3 months ago we had an incident that he described as the most intense situation he'd been in, in all of his years of service.
Long story short, me and at least 5 other officers, whom I work with and would trust with my life, could have (justifably) shot and killed a man we knew to be wanted for kidnapping 3 children (they had already been returned safe).
I've had my gun out countless amounts of times but that was the first time I had my finger on the trigger and damn near pulled...all I was waiting for was someone to say "Gun!" Thankfully, he decided he against whatever it was he was reaching for and, instead, took off in his car. He got away after we terminated the pursuit due to weather conditions on the road. He was caught the next day by U.S. Marshalls.
I don't know to this day if he was armed or not. What I do know is that every single officer there is a good man, well trained, smart, and trustworthy. We each could have pulled the trigger and have been justified in doing so, given the totality of the circumstances (the guy had FB posts indicating he was going to suicide by cop). We didn't but, had we, we would have been scrutinized as being poorly trained, undisciplined, trigger happy cops.
It comes with the territory and, I'm fine with that but, no matter the outcome, we would have been vilified as "bad cops" by some, no matter what details came to light.
That's the job. And I love it.