Paper capacitor longevity

[RetroHacker]

After rebuilding a couple little radios here, I have run dangerously low on .047uf capacitors. On a whim, I punched it into eBay to see what was out there. I was amazed that it came back with a lot of results - for paper capacitors! Old stock, paper in oil capacitors. How can these still be good to use? I know that the paper in oil caps are somwhat better than the common paper in leaky wax capacitors, but surely these will have suffered a similar degridation over the years. I know, that if they were stored properly, they will probably work fine, for a while anyway. But for how long? How long can a paper capacitor, or paper in oil capacitor, be expected to last if not used?

Or is there something I'm missing?

Either way, I think I'm going to stick to orange drops and those little yellow guys.

-Ian