Plenty of items that I have purchased and been unhappy with personally have found their way back to thrift stores.
I try to donate primarily to the more local actual charities that do a lot of good in my community like the salvation army, but I have no problem donating to for profit thrift stores either as I am in them often and I can see the great things that they're doing for a very large number of less wealthy people.
As for finding thrift store items in general, you can find some great things in need of minor tlc, especially hand tools. I tend to use my battery powered told for most things these days that are have tools so plugged tools aren't my forte but I still have a drill I bought ages ago that's lasted me numerous projects and years without failing. It's kind of remarkable how well built some tools are.
That is absolutely a great concern to me, but the fact remains that there are at least 10 homeless shelters and soup kitchens in my area funded completely by the salvation army.
While savers et al might be more supportive of the LGBT community, salvation army is literally putting a roof over hundreds of heads who call my city home every night, which is why I choose to support them.