Where I live there are quite a few charity shops & I regularly see things left outside when they are closed, that look like junk - shabby clothes, rusty old buggies, broken toys etc. This despite many of the shops having notices requesting no donations left outside 'because they may be stolen' (or maybe the real reason is 'because we don't want to have to dispose of all your old rubbish').
Yesterday I was walking home from work & outside one shop was a big old computer, it looked like a vintage 1980s model so big that people were practically tripping over it in the street. Who knows if it even worked....anyway it was being rained on so probably wouldn't be working by the time the shop opened. Surely it must be a nightmare for the staff (volunteers?) to have to deal with 'donations' of this kind?
I think the people do this are selfish and thoughtless, maybe they have had house clearouts and can't be bothered to dispose of all their junk properly....so instead of donating good quality, usable things (which they maybe flog on ebay) they dump their rubbish at charity shops and go away feeling all virtuous. However they are too embarrassed to hand the stuff over when the shops are open.