I just didn't think to offer the disclaimer, since I had sold other stuff that had came from the same environment. Completely my fault and I'm just as frustrated as everyone else.
Well good on you for taking the item back.
But why SHOULD you have offered the disclaimer? It's not your fault, it's the buyers fault. I keep mentioning my "cat disclaimer" suggestion example because I am allergic to cat hair. Cat hair can also damage sensitive equipment. I CAN smell (and get sick) if I get an item that was in a cat environment. Do I expect the seller to "disclose" that they have a cat? Of course I bloody don't. It is up to ME (the buyer) to ask if it was in that environment. If it was any other way we'd end up with Sell items with 42.8 million lines of disclaimers (e.g. "Oh, I ate peanuts once when using the lens"). You Americans do seem very self-centred: Oh, the seller must think of my circumstances... *cry*. To an outsider it seems very pathetic and childish.