Used is a four letter word.
When something has been "used", there is often the connotation that it is a lower quality than something that is "new". Used books. Used cars. We feel like if they are used, there must be something wrong with them. But such is not always the case - many "used cars" are now being sold as "previously owned", with the implication that they are nearly as good as a new car, without the price. Used books have been resold (and reresold... and...) for ages - the text itself doesn't degrade, and a little wear usually doesn't change how well we can read it. Such is the ultimate recycling - continuing to use a product for its intended meaning, giving it a whole new life with a new owner. It is only when items are used up or abused that they are really too used for use.
The downside is that the person that originally sells an item loses out on its "resale", or a sale of a new equivalent item. Many are, unfortunately, trying to prevent items from being reused. Every so often there is an attempt to prevent DVDs or videogames from being re-sold. Many products are designed with a deliberately limited life to make them less valuable on resale and discourage this activity. Fortunately, people still value a solid product that can be used, shared, and re-sold.