In the majority of cases, retailers trash their products (sometimes after physically destroying them) that go unsold. Even for used items, most people are too lazy to donate even things in perfect condition
I gotta admit the grocery store I worked at back in the day was pretty good. They left their old produce for people with animals to take. Employees could take expired stuff that was still good but going to be thrown because it was past the date.
I dunno I don't like wasting things that are good. There's always a better solution than just throwing things away and destroying them.
https://theoutline.com/post/2602/clothing-companies-are-tras...
http://www.slate.com/blogs/xx_factor/2010/01/07/why_hm_destr...
I guess that's why some of those startups that tried to create an "exclusive" outlet prospered (Gilt Groupe, Vente Privee).