Your bumper stickers can indeed determine if you are pulled over or if you receive a ticket. Police have much more descretion than you perhaps imagine.
I get pulled over 2 or three times a year for minor offences. I rarely receive a ticket though. My "Don't Drink and Drive" and my "Texas State Troopers Association" bumper stickers label me as a law and order type. LOL..if they only knew;-)
It works better than "No Fear" or "Party Mobile" bumper stickers. Getting a "Legalize Pot" bumper sticker is like asking the police to pull you over. Don't believe me? Get one.
You're right. A friend once had a bumper sticker that read "I'M NOT AS THINK AS YOU STONED I AM". He had to get rid of it because he kept getting stopped.