My personal dealings with the police have been pleasant. Or at least as pleasant as getting a citation for speeding can be. The officers have all been professional and have done their job. But, then, I have never given an officer a reason to be nervous around me. I don't argue with the man doing his job. I argue about that with the judge, who's job it is to determine who wins the argument.
I don't think that police departments have reached the low levels of corruption and nastiness that many officers displayed in the 50's and 60's, especially where race and hippies were concerned. These behaviors by police are nothing new in the US. It is a constant battle to protect the rights of the citizens against an overreaching government and an overzealous police. Our forefathers understood this and gave us the tools to protect ourselves. Taking back the tools of government will put a stop to most of this..