On the one hand I generally feel bad for cops:
It's a shitty job, but not just that, a shitty life too. You risk your life, you get paid shit, if you are a cop you probably have trouble making friends who aren't cops - so most of your friends are other members of the force (which is dangerously insular), and you have to do tons of paperwork and abide by regulations galore.
The problem is that this results in them taking out a good deal of their resentment on the very people they are supposed to protect - especially the very poor (cough, Rodney King, cough). They tend to prey on citizens, rather than actively protecting and helping them, and send people away for petty crimes like drug possession (which should be treated like a public health issue, if even a crime at all), so that America now locks away more of its people per capita than anyone else in the world (even China). Not to mention the general level of brutality shown to peaceful protesters (RNC 08, cough, Battle of Seattle).
Now, they aren't all bad of course, but I'd say that the good ones are the minority. If your white and rich and in the suburbs, yeah, of course they wont bother you. If your black, or poor, living in the poor part of town, they can make your life a living hell.