Can you touch the tubes?

Touching tube with bare hands is fine and no danger to health. Many folks do that.

I avoid touching the print, lettering/numbers, info on old 1950s-1960s 9 pin signal tubes. The oil from fingers can smear the print on the glass.

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If you look through tube manuals under Installation and Application the only things stated are the socket pin counts and whether or not the tube can be mounted in any position. Since "touching the glass" is not stated (or "do not touch if they glow") you can assume it's something too obvious to print. 

Tubes do not get hot enough for the oils on your fingers to effect them.

This partially stems from the halogen lamp (and others) days as those things get white hot. 

Hello Emerging Soul!  The idea comes from the era when quartz mini bulbs (which run very hot) were introduced. Often found in desk lamps, the tiny bulbs almost instantly heat up to way past boiling water temperatures. Fingerprints leave oil on the surface. It takes time for the oil to heat up and that part of the "bulb" will heat up slower than the rest of the lamp. As all the bulb is trying to expand (slightly) as it heats, the slower heating parts will cause such a stress that the bulb may shatterl It will happen very quickly and the users hand will be in the vicinity as very sharp, very hot fragments of "quartz" will be sprayed about. This is a real problem with projector bulbs. I have replaced many such bulbs without problems, but I always leave them in the plastic bags they come in (after cuting off the bottom of the bag) when inserting them. Then, I just slip the bag off the bulb before applying power. Ordinary vacuum tubes are glass "bottles" that don't run nearly as hot and heat up gradually. Cleanliness and care are always a good idea, however.