That was my dad's idea way back in the mid 50's.... We had a green Pontiac, with a blue right fender, thanks to dad not seeing a chain across a driveway he was pulling into..... never bothered to paint the fender he got front a junk yard.
A buddy of mine used to have a hooptie truck, a '76 Dodge D150 Power Wagon. It was a red truck to start out with, so the red cab was the only part of the original truck, body-wise. It had one dark green and one dark blue front fender, a white hood, black tailgate, yellow and gray doors, and an orange bed. Oh, and big bumpers made from oil drilling pipe! Absolutely no one would park next to it in a parking lot! He'd go out of his way sometimes to find the nicest car or truck in a lot and park next to it. Never caused any damages or any of that; it was to produce a rise and a scare in the owner! That Ranger reminded me of that Power Wagon!
... and still another one. "At some point someone repainted it." Thus ruining whatever collectible value it might have had. http://norfolk.craigslist.org/cto/5082524936.html
Sometimes that happens, but then again, something like a brush with some brush or a tree ran out into the road could've changed the value for them.