My daughter and I volunteer regularly at a Hospice Thrift shop. One of my jobs is to go through the donation bags/boxes/whatever when they come in and sort what is possible to sell and what is not. One little note, for most places that request donations, they are going to turn around and sell the item for cash. It won't go directly to someone in need. (Yes, there are some places that give directly to the needy, but most DO NOT)
So let me give you a few little guidelines:
* No stains. NONE. If there is even a tiny speck of a stain, it's gone. No armpit stains, no collar dirt, no one little spot that if someone just took a little time and cleaned up this Versace dress would be a huge find. It will go straight in the rag bag.
* No rips or holes. That darling little boy t-shirt except for that one tiny hole where the cat's claw poked thru and it's expanded a tiny bit, but the shirt is still wearable? Two words. Rag bag.
* They need to be clean. If you have something that needs to be dry-cleaned make sure it is before you donate. Otherwise. Rag bag.
* Metal hangers. Garbage.

* Gorgeous china plate with that tiny chip on the edge that no one ever sees. Garbage.
* Matching coffee mugs with coffee stains inside. Garbage.
Polishing a manuscript is a lot like sorting through your donations pile. Make sure there are no dangling participles or run-on sentences. Fix that one paragraph that you think, 'oh, it's a bit rough but no one will notice'. Or maybe that section of the plot is like an insubstantial metal hanger, unable to bear the weight of the twists and turns, but I'll leave it there anyway. Just don't. *Don't* put in the bag and send it off.

Otherwise that editor or agent will do the same thing we do with unacceptable submissions.