Are all of these NOS tube inventories real? How have we not consumed them already?

You really just have to do your homework with vintage valves or NOS. 
You need to know what labels, plates, and getter constructions look like, and be able to look up valid date codes. 
The vacuum tube industry was just as incestuous and precarious as the record pressing industry. Many brand name tubes were assembled at other tube companies factories and the tooling changed hands as well. There’s a lot to know. 
Often, someone like Andy at VTS is one who could tell you what’s what. Fore mentioned Kevin from Upscale and Brent Jessee are all good resources, but you pay for what you get. Many other folks are just talking out of their arses. Parroting what someone else has said on the internets. Crazy. 
If high quality signal tubes last 5-10k hours, it’s not much of an argument that they are a value even at several hundred dollars apiece if you find the right tubes, in the right condition, for the right circuit! But now, or cry later. 

If you see a dealer that has a bunch of "new old stock in white boxes" you should be wary. Especially if these NOS are not military (JAN) tubes. A box doesnt prove that the tube is NOS, but the lack of an original box usually is very telling. 

"new old stock in white boxes" you should be wary. Especially if these NOS are not military (JAN) tubes. A box doesnt prove that the tube is NOS, but the lack of an original box usually is very telling.

I find this to be true, of all the tubes I have purchased the only one that failed was one that didn't have an original box.

I am picking them up tomorrow. Will keep you all posted on what we find.

Well, I filled up the Tahoe with almost half of the collection. I thought this was a collection that was purchased from an avid McIntosh collector and where mostly NOS. I was wrong. True he was a McIntosh collector, however the tubes are not mostly NOS, but have all been tested with the bad ones decarded. There are quite a few ham tubes but thankfully no TV tubes, plus some really bazaar ones. This is just half the batch so far but I did get a look at his secret stash, now we are talking. Several bins of Genalex, Western Electric, RCA, Telefunken, Mullard, Valvo, etc. all tested on his Amplitrex tester complete with printout. I will be selling those after all the others are gone. Not sure yet if there are 30,000 tubes, however there are certainly 5 figures total. This project will take quite awhile.