We have not encountered this kind of fake user. Well... not that we know of anyway.

The ones we get are those who report that their item has not arrived or that we have not supplied the correct quantity.

Especially if you can see a history of feedback left for others that indicates they are the most "unlucky" buyers ever when it comes to this kind of thing. So unlucky in fact that they really ought to give up buying on ebay at all.

Since we use regular untracked mail we have little choice but to send out replacements.

After we do we always leave a follow-up to the feedback we left them that says something like.

"Replacement sent for item reported lost in mail <date>." Or similar if it is a quantity extra sent out.

I would like to see every seller leave such a message. That way other sellers can clearly see how unlucky a buyer really is.

And so can ebay if a future investigation arises against the buyer.