how many NOS tubes have to be discarded simply because they went bad in their boxes while sitting unused.
That's an easy one to answer. Based on my experience, just count the number of "NOS" tubes added to ebay each day and multiply by the number of days since ebay was first launched. That'll tell you how many NOS tubes have gone bad sitting on the shelf, because I have NEVER, EVER, EVER bought an NOS tube from an ebay seller that measured close to NOS. In fact, less than half actually measured "good" on a calibrated Hickock Tester.
If one buys tubes that do not measure in the, "NEW" range, on a calibrated tester, but were described as, "NOS," either the seller didn't know what they were selling, or they lied.
Exactly. Either way they were not NOS. My life is far too busy to hassle w re-packing, paying for shipping, and HOPING to get a refund. I buy tubes from dealers w established reps on A'gon or their own web presence and a long history of honesty. I'm glad you've had good luck on ebay, Rodman. I was just venting (pun intended). You are of course correct, as long as the vacuum is maintained, and there are no shorts, unused tubes don't deteriorate over time. IOW, if they are good, they will stay good, assuming that they do not get physically damaged. So if you stock up on new tubes now, and leave them in a safe place, they should be fine when you use them 2, 5, 10, or 50 years from now.