Goodwill is a thrift store. They only have what people donate. Personally with my own eyes I have seen anime and magna books at this outlet store on numerous occasions - usually every few months some might pop up in the kids books or the DVD bin. To answer the other question - yes goodwill does throw out tons of stuff all the time. to deter dumpster divers they pile up trash stuff separately and it gets taken out with the delivery truck and shipped off wherever. what they deem is trash can be decorations that are out of season, chemicals that they think are dangerous (even antique 200 year old kerosene candles), furniture that looks too scratched, and even just large stuff the store has no room for.
This isn't a way to contact the store directly, it's for help from the Google community. But to answer your question, I doubt that they would throw out a donation. If they couldn't sell it, they wouldn't accept it in the first place.
Thanks! Your answer is awaiting moderation.