If you had a dozen pairs of classic vintage ubes in your closet

You will most likely not be able to consistently tell a used tube from new with a simple emissions tube tester. Shorts yes and that is about it. If you buy a tube tester buy a true transconductance tester. Many Dynamic Mutual Conductance testers only test for transconductance on some tubes (B7K 707 for example). 

It is also true that suitcase testers do not test most power tubes are real world levels and as such they do give these tubes a true test. I have found that gm testers like Hickok and Triplett do a fine job on everything but power tubes. 

Most often, these days, the vendor himself did not own the tube from "new", meaning he did not buy it from one of the old time businesses like Radio Shack or Heathkit that once had brick and mortar stores and sold truly new tubes over the counter.   So the seller only knows that the tube looks new and has a proper box to go with it.  That is why I would value sellers that have their own high quality test equipment and are willing to warrant that a tube tests within new specifications.  There are a few out there.  But how did this get into a discussion of fraud in the tube business?  I thought we were talking about the impulse to tube roll.

I have a lot of NOS tubes, in baggies, by type.  I use them as replacement for Gold Lions reissues that fail.  I keep waiting but none of the 12's will fail.  I quit buying NOS Tubes maybe 15 years ago.  Price vs. Performance became an issue as the product became more and more scarce and costly.  Looking back, I was buying NOS tubes to make gear sound better so, I just started buying better gear LOL.

midareff1

here's an active listing that may show the TT

https://www.ebay.com/itm/133653044198

@vegasears I hear you but you can only demo so many allegedly "better" pre-amps and amplifiers at very significant cost levels, and watch dealers leave with the tail between the proverbial legs before you decide maybe expensive NOS tubes are a pretty good way to go. Some vintage gear just simply kicks axx when in a well matched system. Last demo pre was an Audio Research LS 27 and tube guys just don’t or won’t haul 70 pound amps in here anymore for a room full of guys to agree the SS amps were better tonally and detail wise. I just installed half my remaining NOS Siemens and Halske Cca 6922 grey plates (1962 issue). I see a pair for sale at $2K. I used to buy them for $40 each.... maybe 10 years ago I sold some for $200 each.. I should have kept them.    Replacing a vintage pre with a new $16K (or more) unit is not a solution to not buying NOS tubes.