Take #100 Bumper stickers for example:
The safest and most accepted choice for a sticker is always one that supports a Democratic Presidential candidate (Ralph Nader is an acceptable substitute). As of February 2008, white law requires an Obama 08 bumper sticker to be placed on the back of every Prius. Though these stickers reach peak effectiveness during an election year, it is acceptable to leave this sticker on the car until the next election regardless of whether or not the candidate actually won. If it’s a disputed election like in 2000, the sticker can be left on for the life of the car.
As Homer Simpson once said, "it's funny 'cause it's true." I still see Gore stickers on cars in my county.