I have seen those 1/6 and 1/12 listings on eBay. I am especially leery of the 1/12 auctions. Not for the bootleg quality, but that they may not exist at all. All of the sellers of the 1/12 scale humans have 0 feedback and all joined May 13th.
I had won 2 auctions for bootleg figma Windranger and never received anything but a refund from eBay/PayPal. Those sellers are no longer registered on eBay.
I also saw several new sellers of the monsterarts Jackson King Kong with auctions starting at $5.00, I think those were vaporware also.
I am not sure about the mentality of these scam sellers. It is not much money and eBay will surely get it back from them so why bother??
easy, they withdraw the funds out right after payment, try to make as many sales as possible before a flag is waived, they can just keep opening new IDs & accounts, there's 1bil population there so it's not hard for some folks having database of the people and use them to create more accounts. or they can acquire ID from stolen documents.