Cops will usually start out with insults, humiliations. If your girl friend is with you you might hear, "I don't know, she looks like a whore to me" or infer that you are gay. They want to anger you so that you will say something that allows them to take further action. Smiling sweetly foils this to a degree but that you are not taking the bait can anger them but at least they can't legitimately fuck with you. They still can lie and say the most bazaare shit in court.