Let's just think about this in a rational manner for a moment. Maybe these kits were given to a Veteran who lost interest in building them. Maybe someone along the line made a nice donation and the kits were given to the person who in turn gave or sold them to someone else. These kits may have served their intended purpose and have since gone on to other purposes.
I've got kits kits with various stickers from clubs, organizations and what not that I acquired over the years through purchases and trades.Even have a few from Boys and Girls Club which I swapped aircraft for cars with the kids who wanted to trade...either way they got what they wanted and the kits served the purpose they were intended for...giving kids who otherwise wouldn't have the opportunity to have a model kit.
Before you get too PO'd, ask for more information from the vendor. Maybe someone dumped them on him.
Just a thought.
Oh and if I dig around here a bit, I can probably lay my hands on some of the stuff they gave me when I was in the military medevac system and hospitals...blankets, cups, games, toys, nic nacs...organizations were always giving gifts to hospitalized military and Vets. Most of the stuff I left behind leaving it for the next guy, but some I kept. I can remember the tons of donated stuff brought back from GW1...we could have stocked a store with it. Stuff people kept sending that the troops didn't need or even want! But the host country said...if you packed it in, you pack it out! We don't want your trash left behind so our guys hauled it all back home. I had cases of hand moisturizer, pens, paper, envelopes...toiletries just tons of stuff! Most ended up in our shops dumpster cause no one wanted most of it...not even the local charities because it has been overseas and not considered new and unopened...that's another story.