I've been buying some ThinkPad chargers on eBay and never encountered outright fraud. When they say genuine, they really are. Otherwise they use different words.
They usually work, but I've never seen a legitimate name brand coming from Hong Kong via eBay. My experience was mostly in sporting equipment, and the stuff that I ordered looked and smelled like it was "Adidas" or "Nike," and even said "Nike," but it obviously wasn't made by Adidas or Nike.
Lots of actual stuff is made (or shipped) from Hong Kong. I don't know enough about the specifics of Lenovo, I'm just saying I've bought and sold hundreds of thousands of dollars of items on eBay, and I've never yet seen a "genuine" name brand on eBay that shipped from Hong Kong that was actually legitimate.
If I had to bet money on it, I would guess that these are the same type of things that you find in Chinese "fake markets" - name brand items that would pass as name brand to anyone who is not very, very familiar with the brand. If it works it doesn't matter in the end, but I've seen some real duds from those types of markets, as well. Maybe they "fell off the truck," but my money is on that they're fakes that are designed to resemble the real thing as closely as they can.
I wouldn't be so trusting. In the best case they are real, or ghost shift production. In the worst case they are fakes that have all the safety features cut out. There's no way to know unless you open them up.
I ordered one yesterday (not from this dealer in question) that also said genuine. Let's see what they will send to me.