Without going into too much detail, my family has had to deal with a cop doing the wrong thing. He is still an officer. He was actually promoted a couple years back. I hate him and avoid him at all costs. My grandfather was killed by an officer not following proper procedure.
On the other hand, I got know a great officer that ended up being killed in the line of duty. Murdered actually. He was a great guy and a big help to me when I needed it.
There are bad ones but I think they are quite rare. I have a lot of respect for them.