Reliability of Yahoo Auction

I purchased a fair amount of my cels from Yahoo Auction through a third-party (J-Subculture), and have not been disappointed so far. That said, since Yahoo Auction is Japan's equivalent of eBay, I have seen quite a few shikishi that I want but am hesitant to buy. Not because of the money, but because of the high chance that they may be fakes. Does anyone here share the same concern? If you have purchased shikishi before from this auction site, what was your experience?

It depends I try to purchase Shikishi that include the winning notification from the Magazine it was given away through lottery. And I also try to stay away from Super Popular expensive Mangaka..

99% of shikishi are fake on yahoo

That's only true for very famous artists, like Eiichiro Oda and Hayao Miyazaki. 99.9% of all shikishi on Yahoo Japan attributed to famous artists are fake. If you're after artwork from lesser known artists, you won't have a problem. I would look for winning notifications, and run the person's name through Google to do comparative image analysis. Eventually, you'll see a couple sellers you know and you can largely trust their listings. I've bought a good chunk of my original artwork on Yahoo Japan and it is all legit.

I bought a few signed/sketched lesser-titles, like Gamble Fish, and the artwork looks legit. Some of the larger titles, like One Piece, DBZ, and YYH look completely fake, though. Heck, my Kurama done in high school looks more legit than three I've seen. And then I see a Naoki Urasawa sketch that looks legit at first, but has no supporting proof of its vapidity. Thanks for the help, everyone!