I don't buy old photo paper. Like most of the old film cameras these days that are not already in the hands of collectors or users, most of it is trash--and increasingly expensive trash . We've all seen the e-bay posts where sellers open the paper pack and fan out the contents to take a photo for buyers. Understandably, for most, the basic knowledge of storing and handling light sensitive material has been lost to history.
That didn't used to be the case. I used to buy every pack of old photo paper I saw. Sealed, open, part used, it didn't matter. Most of it worked fine, even for conventional...