Sad how the last season ruined it. All characters lost their senses.
During the final season McNulty flipped the script and began behaving in the same way that the city/department behaved.
It was purely to illustrate that if a human behaved the way that the Baltimore Police Department behaved you would view it as a self-destructive deranged person surrounded by a cast of enabling supporters with questionable morals.
I, personally, thought it was brilliant.
Season 5 loses that feeling. While it was completely enjoyable, I think it was missing something.
then, consider what the writers of the Wire did throughout the entire series, especially in the previous season's story arc about the "Nailgun" serial killings of Marlo's enforcers Chris and Snoop in the city's vacant buildings.