you're still avoiding the moral argument - that to me seems obvious - whereby the owner of something (not the seller) appears to have no say in how the images of their possessions may be used. It would appear obvious that if an owner is not contactable, then images of their goods should simply not be used - or if the image has been used because it belonged to a seller, then at the point of sale that image is no longer freely available.
It's obvious that an ebay seller is unlikely to object - they are parting with the goods and have no interest whatsoever once they've posted the 'something'.
My point is simply that there is a moral argument in favour of courtesy in requesting permission from the owner, to use a picture of something they own, and if you can't find the buyer then the image should not be used.
Owners/collectors invest their capital in the goods - they insure them, pay for cabinets with which to display them, frequently research the object, often make their object available to others on internet sites - and then turn round and find that they have no rights over the images which, in some circumstances, might be used for purposes with which they may not agree.
We've been lucky in recent times with, for example, the National Archives and the V. & A. Museum - time was they'd never have agreed to images of their possessions being used by anyone, watermarked or otherwise.
I'm not trying to disagree with you deliberately Christine, I don't for a moment doubt your knowledge of the laws of copyright in view of your work - it's just that I feel the law in this instance is being mis-used (and I do frequently consider the law an ass). None of this is to say that an owner/collector won't give permission for an image of their goods to be used - I'm suggesting we owe them a little more than a dismissive waive.
I'm fed up with using a lap top - missing my mouse terribly - so will leave you to have the last word, and promise I won't reply.