Can you touch the tubes?

If a tube has a separate base, you pull and push it in by that base to prevent separation of the base from the glass envelope.  But there is NO need to be concerned about oil being deposited on the glass.  That concern comes from what happens to some types of light bulbs.  Oil deposited on the glass of such bulbs carbonizes from the intense heat.  That black spot will absorb light from the bulb, rather than letting the light pass through, and this causes that spot to heat up so much that the glass fails, which causes it to explode.  This kind of heat an light production never occurs with audio tubes.

If a base is loose, even completely free of the glass envelope, as long as the wires are not cut, you can glue the base and glass together.  I use high temperature epoxy, but I have no idea if that is the best glue to use.

It is not that common for the base to come loose unless a tube is really old.  I run 70-80 year old tubes so I am careful.  Some not so old Western Electric 300B reissues had weak glue joints so care is needed.

I have never heard of anyone squeezing or pinching a tube so hard as to shatter the glass, but I suppose that is possible.  Aside from dropping a tube, the most common accident is inserting a tube incorrectly so that the pins are in the wrong holes.  That can happen if the key on the central post, or the post itself is broken off so thar a tube can be inserted even when incorrectly oriented.  Some 4-pin tubes, like 300Bs, don’t even have a key and rely on two of the pins being fatter; unfortunately, they are not fat enough that they cannot be shoved into the small hole of most tube bases so that a horrible accident is possible. 

I had metal halide bulbs over s fish tank.  The fixture had a safety glass.  When a bulb exploded (near its end of life, a common occurrence) a few glass fragments were so hot they fused with the safety glass.  I’ve also had tv projector bulbs explode (also metal halide).  As I explained above, failure from skin oil happens with such bulbs because the oil carbonizes from the heat, turns black, and the black absorbs the high intensity light instead of letting the light pass through, and it is this additional heating from absorbing the light that causes failure.  Even if a carbonized black spot did develop on a tube, it doesn’t give off enough light to cause overheating; the tube will NEVER fail this way.  I’ve seen tubes marked by permanent markers; there is no harm from this.