I bought dd a wooden marble run yesterday in a charity shop. The box was sealed with tape but it looked fairly new. When we got it home and opened it, many bricks were missing and had been swapped for odd bricks which are different sizes to the originals so they don't stack up to the right height to be able to use it properly. There are no marbles and we don't have any of the right size to fit through the small holes...not even sure that you can buy them that small. DD was disappointed but being 3 quickly moved on!
I won't return it because it would feel like taking from a charity but I do feel cross with the people who dontated it knowing it's junk. I was just interested in what people thought of returning something worthless morally. It was £8 if that matters.