Why does NYPD hate young ethnic people so much?
On the job training. If the human brain does one thing well it is pattern recognition. Unfortunately 45% of blacks live at or below poverty and it isn't middle or upper middle class people commiting most of the crime. When 80% or more of the crimes you are dealing are commited by people of a certain skin color, dressed a certain way, speaking in a similar way... you learn to associate this category of person as a danger and even eventually with all the crap you deal with day in and day out as degenerate or less of a person than you.
I would imagine that even the best of people would tend to come out of a tough police precinct as 'racist' to one degree or another regardless of their intentions or the type of person they were when entering. It would be something you would have to constantly guard against. It is a depressing problem to consider. I'm not sure how you would even combat this. Mandatory participation in things like the big brother program for the neighborhoods you police? Other community involvement while off duty?