Tube Question--Signs a tube is brand new

I just received a box of 25 6550 tubes off ebay which were listed a Never used Sovteks from the early 90s. The seller has 10 boxs of 25. He stated that they were NOS and never installed in a unit. I just tested 3/5 of them and they all test in the middle range of "questionable" on my tube tester. I have some older GEs which test "good" so I know my tester is accurate.

Is there something within the tube which indicates if it has been in operation for a period of time? I compared some of my used 6550s and the top and bottom round plates look grayish and identical to the ones which were just sent to me and supposedly new.
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If they test questionable then it really does not matter. That is not an acceptable "new" tube.
You can look at the pins and see if there are telltale scratches on them which would indicate that they have been inserted and pulled from sockets. Using a magnifying glass will help.
there are bad (b stock quality) new never used NOS and good (a stock quality) new never used NOS tubes, i suspect the former...
There are alot of people selling tubes on ebay. The Phillips that I just purchased humm quite loud on my system. This does not mean they are fake just B stock or just bad. This happens. I got a great price and got bad stuff. I will stick to known sources for tubes, tubedepot and the like as they take bad stock back. Live and learn!