As the hot glue story seems to be of ever more interest, and now sugar
is mentioned, let me add that to the best of my knowledge, a kind of
very simple sugar (glycerol or "glycerine", as it is also called) is
added to prevent the glue from becoming so hard and rigid when set.

This might be an advantage when leathering organ bellows for example.
It presumably does this in the same way that it works in cake icing,
through the glycerol being deliquescent (absorbing moisture, and
dissolving in it) and this keeps the glue from drying out completely.
I suppose, if you wanted a tasty snack of impure gelatin full of dead
and dying microorganisms, it might also make it more palatable too.

Paul Morris