I used to volunteer in cancer research charity shop and you should have SEEN how those old ladies fell upon the bags! They went through them all, picking off what they wanted. You were supposed to pay, but these were the same people pricing everything up! so I just bet they went for a fair price and didn't knock themselves off a bit.
They had a shelf where they'd put the stuff that they were 'buying'. Everything else got sorted and tagged and taken downstairs to the shop.
I do have very poor social skills, Fennel , but I was working in a bar, volunteering at relate and doing a job trial 3 buses away at the same time!
Don't know why I felt the need to clarify that! think it was the "You have to think though what sort of people do volunteer in charity shops. " thing