What do thrift stores do with unused/unwanted donations?

I have started volunteering at a local Women's Resource Center thrift store. Many of the clothing items are donated (directly to the thrift store) in unsellable condition. These usually get thrown away or put out on the Free Rack. Clothes that have been on the floor for a month or more and have not sold are supposed to go to the free rack, but if there is no room on the rack, they just leave it out on the floor. So then there is no room for the new stuff. This stuff is usually stained or just outdated, some good stuff. They have bag sales every so often and a 3 for $1.00 sale once a month on clothes. How would I go about finding somewhere to re-donste the unsold clothes? They used to give it to a church, but they stopped because the church only wants stuff with no stains. Any advice? This place is in Oregon. Thanks.