On several occasions I've handed stuff in to charity shops and been gruffly told to dump it somewhere. I've only had a thank you once that I can recall. Today I phoned to check whether they actually wanted what I had and was told 'no, we don't' and hung up on!
I don't give them rubbish - usually laundered and folded clothes or clean toys. AIBU to think that manners would be nice? I can see a return to freecycle ahead.