I can't imagine the stress and toll that particular job would take on an individual officer, it must weigh so heavily upon them. I know I couldn't do it, I'd just want to bitch-slap those sob's into next week. Very grateful though that some have the fortitude to do the job that is required.
As to the secondary, or perhaps primary, issue of the condemnation of many based upon the actions of the few, this isn't exclusive to police officers. People that take that jaundiced a view of all police officers are simply the type to wear blinders, no different than those who condemn all religions based upon the poor behaviour of a handful of religious people or those who condemn all persons of a particular ethnicity based on the actions of a few members of that ethnic group. There is no differentiation between individual actions and group behaviour in their minds. It's a type of bigotry.
Where it becomes truly problematic is that it creates an us against them dynamic and actually makes it more difficult to weed out true poor behaviour. As we see with the police time and time again, when there is questionable behaviour of one or a few members of the force, the impulse is to "close ranks" because it becomes about protecting themselves against the onslaught of those who would paint all of them with the same tarred brush. In effect it creates a bigger problem.