The more demand there is for something, the easier it is to sell  Any junkyard will buy a used car that is less than ten years old, because the parts can easily be resold  However, because there is little demand for car parts that are ten years old or older, junkyards tend not to buy those cars
Thus, used cars that are less than ten years old are generally easier to sell than are cars that are ten years old or older
The salability of something is not influenced by any factors other than the level of demand for it.