Just handled a speeding ticket in a local court. Met with the trooper to discuss the case. He reviewed his notes. Aha, he said. There's your problem. He pointed to the word "Attitude".
I knew exactly what he meant. This client had been difficult with me as well, and I remember from speaking with him that it sounded like he'd been difficult with the court staff as well.
So this particular client did not get the same deal he would have gotten if he had been polite to the Trooper. I still got him a deal, and this deal was significant, but it would have been better still if only.
Remember, police are people too. Most of the police I encounter in my work are pleasant. They believe in what they're doing (no matter how many of them I see speeding with a cell phone at their ear). So be nice to them. Respectful. Because you should be nice. But if that doesn't work for you, then because you won't get as good of a deal if you're not nice.