Dented appliances are not necessarily used when sold. Some appliances become dented during transit or at the warehouse, and cannot generally be sold for full price.
Many dented appliances offer the same functionality as their undamaged counterparts, but come with lower price tag because of the cosmetic damage. Some sellers offer limited warranties on dented appliances, while others may be sold as-is, meaning once the appliance is purchased, it is no longer covered against damage or failure.
Many appliance stores offer slightly damaged units for sale in their showrooms, as well as brand new and used models. Dented appliance stores can generally be found in local phone directories.