At work we were collecting for a food drive at Christmas and someone donated swollen, rusted cans of food. I was shocked. Who does stuff like this?
Some are just mean people, but I think some are borderline hoarders. They can't put something in the garbage, because that's "wasteful". By giving it to charity, they reassure themselves that "maybe someone else can get some use out of it". Even if they learned the charity threw it out, they'd feel OK, because *they* didn't throw it out themselves.
Unfortunately, I think a lot of advice on frugality and/or waste reduction is harmful to the psyches of these people. I'm a bit of a hoarder myself, and sometimes I have to bite the bullet and say, "this may end up going to the dump, but that's better than sitting in my apartment, then
going to the dump when I die."