It's a service-oriented job that attracts people who like to control other people. There are only so many upsides to a situation like that. Here's my favorite take on the subject:

"Police business is a hell of a problem. It's a good deal like politics. It asks for the highest type of men, and there's nothing in it to attract the highest type of men. So we have to work with what we get—and we get things like this."

- Raymond Chandler The Lady in the Lake