My family has an odd superstition about dealer decals on our cars. My parents' 1981 Olds Omega needed some body work done on the back end after some vandalism. In the process of the repairs, the dealer sticker came off the car. Afterwards, the Omega started having engine troubles, going through thermostats at a rapid pace.
My parents ordered a 1989 Olds Cutlass Calais that came without a sticker on it. The fuel pump failed before the odometer rolled past 50 miles. After it was towed to the dealer, Mom asked our salesman if "now that bugs are worked out of it, you'd be proud enough to claim the sale and attach the sticker." The car only had the typical repairs after that point.
When my parents ordered a 2002 Olds Intrigue, they agreed to sell me their 1994 Olds Cutlass Supreme. The Supreme's dealer sticker was starting to peel off the trunk lid. They told their salesman that it was a condition of the sale of the new car to get a new sticker for their old car before it was transferred to me. (They've only dealt with the same salesman for all of their cars, even though the dealer was Fisher Chevy Olds in 1980, Nelson Chevy Olds Geo in 1993 and Crown Motors of Negaunee in 2001.) He dug up some old Nelson's stickers he stashed before the dealer name changed earlier that year.
My current car is a 2003 Olds Alero, bought from Crown Motors. Like its predecessors, the new owners always kept their iconic UP-shaped stickers, and since I used the same salesman, I'm the third generation of the family to buy a car there. Between grandma's old car, my parents' old car and my current car, I've owned cars with three similar dealer stickers all originally sold by the same salesman . Sadly, Crown has since sold to Fox Motors, and the UP-shaped stickers are a thing of the past.