What kind of test did the buyer do? did he need an adapter? some tubes & testers need a special adapter so pins will fit correctly and power the cathode.
When all is said and done the only meaningful test is for emissions, above 70% of spec all is good. The shunt setting for transconductance is the most meaningless test, most testers just output an arbitrary number so you can tube match a pair.
The most important initial setting is the voltage line level, adjust it at power up and again during emissions test, the small voltage drop when the heater fires up will skew the results if not re-adjusted correctly.
I would also skip all those fancy tube testers and get a cheap and simple emissions tester. Take a picture of the meter with tube and include in your auction.
