Vic Mackey was an out-and-out crook. Sure, he did some of the bad stuff he did to catch criminals, but a lot of it was out of self-interest. Remember, in the very first episode he kills another cop in cold blood just to cover up his crimes.Likewise, Vic Mackey did horrible things but he was working to clean up the streets.
If that's the sort of "noble reasoning" you can accept then you'll have no problem with Breaking Bad.
