I have to do that differentiation with the Dexter and True Blood books when I watch the shows. If I want to like the shows, I have to like them independently from the books otherwise I'll drive myself crazy trying to compare them.

Also, just from what I know about cops and what I learned in college as a Criminology major, I'm guessing that a lot of the swearing is to put on a tough exterior to deal with what their job entails everyday. Especially female cops, because they're constantly having to measure up to the men and prove themselves worthy and not show any weakness or fragility (that last bit is true of all cops though).