Discount stores often get products that are close to their sell-by date, stores that close and sell off their stock at discount, products with minor errors on the packaging, etc.  It's not just food- anything can be salvage.  Food that is salvaged is usually technically still safe to eat, but you have to be careful and make sure it wasn't recalled or is spoiled.  Something tells me that the Slaton siblings aren't too picky about what they eat, though.