We often judge that old objects or objects used by admired celebrities are worth less when cleaned, possible because cleaning removes valued historical traces, and by changing objects from their historic state

The glow of grime: Why cleaning an old object can wash away its value. Merrick Levene   Daisy Z. Hu   Ori Friedman. Judgment and Decision Making, Vol. 14, No. 5, September 2019, pp. 565-572. http://journal.sjdm.org/18/181204/jdm181204.html

Abstract: For connoisseurs of antiques and antiquities, cleaning old objects can reduce their value. In five experiments (total N = 1,019), we show that lay people also often judge that old objects are worth less when cleaned, and we test two explanations for why cleaning can reduce object value. In Experiment 1, participants judged that cleaning an old object would reduce its value, but judged that cleaning would not reduce the value of an object made from a rare material. In Experiments 2 and 3 we described the nature, age and origin of the traces that cleaning would remove. Now participants judged that cleaning old historical traces would reduce the object’s value, but cleaning recently acquired traces would not. In Experiment 4, participants judged that the current value of an old object is reduced even when it was cleaned in ancient times. However, participants in Experiment 5 valued objects cleaned in ancient times as much as uncleaned ones, while judging that objects cleaned recently are worth less. Together, our findings suggest that cleaning objects may reduce value by removing valued historical traces, and by changing objects from their historic state. We also outline potential implications for previous studies showing that cleaning reduces the value of objects used by admired celebrities.

Keywords: object value, old objects, cleaning, psychological essentialism