I think the claim issue has mostly been covered, but did just want to point out something, and I'm primarily mentioning it for any future items you may list, but also because it might have a bearing on the outcome of this case (potentially putting it more in the favour of the buyer, even though personally I think an INAD is an unfair claim in this instance):

Used clothing policy:

"Used clothing ... can be listed on eBay as long as it has been cleaned, is stain free, and does not include adult or inappropriate content within the listing."

http://pages.ebay.com.au/help/policies/used-clothing.html

I thought I'd also mention that when eBay clarified this criteria (or rather, attempted to 😄 ) for used clothing some months back, there was some discussion on the boards as to what constitutes a stain (eg yellowing which you might find on vintage clothing vs wine stain on a modern white shirt, the former generally being more debatable / acceptable than the latter, at least among members - no idea where eBay stands o_o ).