i always try and be pleasant when dealing with "the filth", but if they get snotty i just clam-up and give them "the look". never argue, be as respectful as warranted.
traffic cops are the only ones i ever worry about nowadays, and they don't seem to care if you have drugs, as long as your "licence plate is affixed to the vehical in the proper manner".(that was my last one) . the one before that was for a seat belt infraction, i had a young lady with me at the time and the cop looked at her and asked me if this was my daughter (obviously trying to be a ****.)