Besides everything mentioned here and all the stress it adds to the buying experience, this is hurting the relationships in the community as well. Maybe it's just me but I have bought around 20 steelbooks this month and for a few of the high value ones, I found myself having to drill the seller with questions on the origin of the item, where they got it, and have to ask for a picture of every inch of the book.
People who are collectors themselves are usually understanding of this behavior but when it's just a regular person who happened have got lucky and bought the item on launch, they get annoyed pretty fast.
Here are a few sellers on eBay that I am aware are selling these custom books, just FYI:
mapcustom - based in UK
kev2a1988 - based in France
l2kid2l - based in US
They are making sleeves too now. I am not talking about putting on a transparent sleeve with nothing but a PS4 logo, sleeves exactly identical to the original with the text and images and artwork. I almost fell for one a few weeks ago, thankfully Spect3r stepped in and warned me last minute. There was a slight color discrepancy in the PSN logo and the blu ray logo at the bottom.
This was for TLOU RE which was also mentioned by Coelacanth above. They might be trying to get this one right since it is selling for high prices
Fake vs Real below
https://freeimage.host/i/dU7Ils
https://freeimage.host/i/dU7TUG