How can you tell when tubes are shot?

When I was in the Air Force, I worked on a few systems on
B-52's that had tubes..and we had tube testors..but they
don't tell the whole story. A Ferrari and Porsche could
look almost identical on paper..or in Road & Track test
results...but still "feel" and drive very different from
a driver's perspective.... and an old tube could still look
to be good, when indeed it would sound poor, or two of
the same model tube from two different makers could both
measure the same..but sound very different...IE: trust your
ears.

when i need to know if a 9v battery is still good i touch my tongue to it. i'm guessing you could do the same to the tubes while they're in the amp. i'm going to test mine right now.

WARNING WARNING WARNING

ignore previous post. ignore previous post.

Guess the girlfriend wasn't around Kubla?

Kubla must be an Army guy.....in the Air Force we were so
macho...we used "other" body parts to test electical
voltages....let alone keep the curl in our hair!