I think there is a large amount of pessimism involved with people who don't trust any police at all. But the argument "not all cops are like this" when we are talking about an incident isn't helpful, either. Yes, not all cops are like this.
Does that mean there isn't a problem in the profession.
Obviously there is a serious problem in our police departments. Citizens shouldn't be afraid of the police, yet there's a significant portion of the population that is. There's a problem with police administrations where this kind of stuff happens. Like
@rickybobby said about teachers: they aren't all perverts, but when you find out a teacher who had issues with students in the past gets hired in a different district, that's a problem in the industry. Pedophiles priests that can shipped overseas: that's a problem in the industry. Unarmed civilians (or legally armed civilians who haven't drawn their weapon) getting killed by the police: that's a problem with the industry. Doctors who work 26 hours straight and then make a mistake that costs a patient their life: That's a problem in the industry.