I once bought a shimano mtb chainset off ebay (still using it actually), it came rather crudely packaged in cardboard that had originally been a box for cans of dog food and it stank of cheap dog food and shite. I was surprised they'd taken it at the post office it was that bad.
Coming at it from the other end though, another chainset bought from ebay, before I'd even fitted it I decided to use something else so relisted it. Put up lots of photos, explained that I'd bought it, not used it etc. Anyway, I got neg feedback because the chainrings were not cleaned to the buyer's satisfaction!