It's rare because he says it is, nothing more. You guys shouldn't be shocked or surprised by anything you see in eBay listings anymore. From the dozens of listings that have this or that manufacturer's name in the title, just to hook searches, to the dealers who label things as "old", and therefore, justifying the high price, this goes on. And it's not a new phenomenon, caused by or restricted to eBay. Go to any flea market or antiques mall, and you'll find a percentage of the merchandise on sale that is mislabeled, or not identified more specifically than a general label ("toy soldiers", but we can see that it's Heyde's "Triumph of Germanicus", or any figure wearing a tricorne labeled "American Revolution").
If we give a seller the benefit of the doubt, we can excuse him, perhaps, as someone who sells a lot of things from many categories, and may not know too much about any of them. In that case, he probably ought to educate himself just a little. If the seller claims to be a specialist in a given area, or even expert, then we might question his motives.
In any case, it's up to us as buyers to educate ourselves, and if we find we know something the seller doesn't, or if we've caught him in a mistake or lie, that's often to our advantage in haggling. Or we can choose to avoid him.
But I've seen so much of this that it doesn't raise more than a "meh" from me.
Prost!
Brad