Depends what they are. Liquids/cosmetics get thrown. Clothes, electrical, household stuff, jewellery and similar stuff get checked, made pristine again if need be (eg jewellery is re-buffed), repackaged and put back on the shelf for resale as long as they're still in perfect condition. Sometimes, if stuff is end of line and returned but in good nick, it will be put in either the outlet shops or sold to staff in the warehouse shop.