I generally haven't had the best luck with police (maybe because I'm usually breaking the law when we have interactions), but this is mostly choices I make regarding my lifestyle. So ... people have to do their jobs (begrudgingly sometimes), and you'd be suprised how far a little courtesy can get you.

Treat police with an ounce of respect and you'll be suprised at what the outcome will be sometimes (especially when they're being forced to write tickets for something they feel is a waste of their time).