When I was a young punk kid, all cops were "pigs". They were all on the take, and none of them could be trusted. I hated them.

When I was 20 years old, one of those "pigs" picked me up on a drug possession charge, an arrest that ultimately started me down the path to sobriety.
At first it was HIS fault. As if he were the one that sent me into the city with a carload of losers, and HE took the money out of my wallet, and HE put a bag of drugs in my pocket.
Looking back on it, that "pig" saved my life, and I hope for a chance to someday shake the man's hand and tell him "Thank you."

Fast forward a few years, and I started to grow up. I came to realize that cops are just people, trying to do a job. I learned that the best way to deal with a cop is HONESTY.
"Do you know why I stopped you?"
"Yes, sir. I was speeding, etc."
"I'm letting you off with a warning. Slow it down and have a good night."

Since I "grew up", I haven't had one single problem with a cop. Not one. I've only been written up for one ticket in over 12 years, and I've been stopped several times. The one ticket I've had in 12 years was for speeding on an interstate highway, out of town, on 4th of July weekend. Seems I was asking for it.

Point being, you are the single biggest factor that will decide how your interaction with the cop will go. If you think it over, that rule applies to anybody you are dealing with. The first few seconds set the tempo for the whole interaction. If you are pleasant and polite, the cop will be too. If you are rude and nasty, guess what.

I'm glad I grew up. It makes my interaction with policemen go a hell of a lot smoother, and in some cases, enjoyable.
It's a tough job, and they deserve some respect.