LAPD was a cesspool of corruption in the '40's and '50's, but was cleaned up considerably under Chief Parker in the early '60's. For the next 20 or so years it was a model department. And then... well, you know the rest.
It wasn't a model dept. to the citizens and to the thousands who experienced their "kick first and ask questions later" style.
I never crossed them or had to deal with them but I watched them in action many a time and saw a lot of out-of-control behavior. Well, it would be called that if you or I did it but they used it to totally control people that showed not the least bit of resistance or rudeness.
LA cops were nasty bastards in the 1960s. The King incident was no surprise.