One of Life's Unanswerable Questions

Why do people leave bumper stickers supporting candidates from past elections on their cars?  Win or lose, you'd think they would get them off at the first opportunity.  If your candidate won, I'd think that when they screwed up, and they will screw up, you wouldn't want everyone to know that you supported the jerk.  On the other hand, if your candidate lost, even though there is some satisfaction in being able to say, "I didn't vote for the jerk who got elected," everyone knows that candidate you did vote for would have eventually screwed up if elected.