Well bro, in my opinion the trend of degrading car price due to touching or repaint is not justified. As far as I know, there is some point to avoid a repainted car or touched car, as the car might have involved in an accident and there could have been some damage to something or someone else from the environment. If the car owner has made an illegal escape from a damage and then he tries to get his car repaint or touched to cover up the facts, then there is reason to avoid such a suspicious car.
However, I strongly believe it is not the case with the 'price reduction' for repaint and touching, as done here nowadays. The buyer is likely to demand a price reduction for a repainted/touched car even if the car owner has proof of not involving into any legal damage done to the surroundings. Further, the buyer himself does not seem to have even the slightest idea for reducing car price for paint. After all, I don't find many people here who have feelings for a car's artistic value like of original paint. It just seems a culture here.