reading more into it, it sounds like it does not matter if the item is in doubt of being worn.

In Australia Sellers of Intimate aparel Have the right to refuse refund and only offer exchange if the faulty item is returned in the same original unworn, unwashed condition the item left the premises of purchase in.

And that is to protect the seller because you can not mark intimate aparel down and put it for re-sale once it is worn.

eBay YOUR BREAKING AUSTRALIAN LAWS