I can only speak for where I live.
First, two very generalized statements: The Salvation Army’s mission is to directly assist those in need. Items donated to the S.A. may be given to those who need them or sold to provide the S.A. with operating funds. Goodwill Industries’ mission is to provide job skills training and job placement assistance to those who are typically considered marginally employable/unemployable (e.g., people with developmental challenges). Items donated to G.I. are sold to fund its training programs and provide operating funds.
Once again, this is a simplified generalization which I’ve included mostly because I think Goodwill would much prefer to receive cash donations [rant] rather than the tons of broken, stained, mismatched, missing-important-pieces-of junk often left piled on their doorstep in the middle of the night when the attendant isn’t there to tell the “donor” they need to take their cr@p to the landfill and pay the dump fee rather than saddle Goodwill with it.[/rant]
I never donate clothing that is stained, is missing buttons, is ripped, has opened seams, frayed cuffs, etc. to a thrift shop. Clothing with minimal damage I will wash and dry, then take to places where homeless people gather to receive food, medical attention, and other assistance from local charities. I leave the clothing there for anyone who needs it. I donate used bras at these locations, but only if they are still wearable (no rips, loose seams, stretched-out elastic, etc). I never donate used underpants or socks with holes. I occasionally buy deeply discounted/clearance-priced new underwear from stores and include that in the clothing for the homeless.
Another option is to donate “gently used” clothing to shelters for battered women. They often escape their abusers with only the clothes they (and their children) are wearing.
Hope you find this info useful. Regards,