My guess is that Dell laptops have incorrectly vulcanized rubber. During vulcanization, sulfur compounds are added to rubber to make it more elastic. Cat urin

My guess is that Dell laptops have incorrectly vulcanized rubber. During vulcanization, sulfur compounds are added to rubber to make it more elastic. Cat urine also contains a high amount of sulfur compounds. If Dell's suppliers got the vulcanization process wrong, sulfur could be leeching out of the laptop's rubber components.