Some are good, some are bad.
For example, motorcycle cops will give you a ticket for going like 5 over the speed limit because they have nothing else to do. Bad.
Meanwhile another cop will be chasing down someone who just beat and robbed some woman, subduing him in a non violent manner. Good.
Cops are trained to be defensive, and to do no more harm than tackle the subject unless it's an extreme circumstance. Sure their rights state that they are allowed to resort to violence and force if they feel threatened, but that's not what they're trained to do, and that's not what any reasonable person in the police force wants them to do.
Their job, in a nutshell, is to prevent crime and harming of the innocent from happening. However, some of them go about it the wrong way. Instead of profiling, being on constant watch and patrolling to look for suspicious activity, they go about making examples of people and showing what horrible things will happen to you (such as getting beaten by cops) if you commit a crime.
Think about this, people shouldn't be scared of cops. They're here to protect us aren't they? We shouldn't be scared of them, and yet we are. If there's a cop around you, even if you're doing nothing wrong, you're scared because you know what they can do to you.
