I bought a pack of Harco Fold-O-Hinges 'vintage' from an
ebay vendor last year. Didn't get around to using them until last month when I discovered none of them were gummed.
Vintage hinges are a hot commodity and I suspect the bottom of the barrel has been reached and a lot of what is offered are the dregs. Stuff set aside as defective stock years ago is now being sold by vendors who may not be aware of what they are selling. I also suspect some modern hinges may be repackaged in perhaps counterfeit packages to make them look like older ones. With prices up to $15 a pack why not?