#1
So I have a tube amp and I don't mean to sound like idiot but when changing the tubes in an amp is it bad to touch them with your bare hands transferring the oil on them to the tubes?
#3
No. This will not hurt them. Remember - the manufacturer stamps his logo on them. The only thing you don't want to touch is the pins. Try to avoid touching them so they don't build up corrosion.

Avoid touching the glass on halogen bulbs. This will create a hot spot, which will lead to premature failure.
#4
I've been using tubes for many, many, many years and have never had one fail due to fingerprints on the glass envelope. I've got tubes with dates as far back as the 60s and they still perform flawlessly.
#8
You probably shouldn't touch them while the amp is on--they get really hot.
#9
Beside when they're hot there's nothing wrong with touching them. Considering I never use gloves my tubes must be covered in oil, they still perform flawlessly though.

The fingerprint is like steven said, pertaining to halogen bulbs.
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