My experience with the police is that they will usually treat you as well as you let them.

If you're well-dressed, not acting 'suspicious,' and talk to them without putting on a wise-guy attitude, you'll probably slide past what might get somebody else a ride. Of course, the operative words here are 'usually' and 'probably.' They get up on the wrong side of the bed, too.

A cop friend of mine has a little test he gives people when he's talking to them: If they look up to the left before they answer him, he says they're looking for a lie. Much better to look him in the eye and give direct, brief answers. Oh yeah, and call him 'Officer.'