A quick question related to Amperex Bugle Boys

Well the very best by far are the units which allow testing and tracing at numerous operating points. 

Getter flashes should be either silver or can be darker. What you dont want is translucent. A very good test for strength are life tests. If your tester doesnt have a life button simply lower the filament voltage 1 setting and compare these test results with the data from the normal or correct setting. 

Tsushima is correct with the assertion that gm values from tester to tester are not universal or constant. Each tester can be idiosyncratic and test certain types higher or lower than the norm. To know the life left by testing you would need to know the test results when this tube was new as new tube values of the same type and manufacturer can vary by up to 25% sometimes more.

Yes you are correct. Almost impossible to fake the acid etched codes. After a great deal of experience, you become aware of the internal structure of certain types from certain manufacturers. Even the thickness and shape of the glass become familiar. One of my greatest irritations currently is the contention that Sylvania Bad Boy 6SN7s extend beyond the true bad boy which is a very distinct tube.