The tinker wrote: "My understanding is that hide glue never goes bad
(as in loses effectiveness). It will get moldy. Then it stinks to high
heaven. Refrigeration stops mold growth."
It does very definitely go bad, very bad indeed for some uses, though in
other uses you might not notice the problems." 

Got no idea how anyone manages to gets mold growth and high heaven stink
from liquid hide glue.  I've never had that problem nor heard of it.  I
bought a case of Franklin liquid hide glue 30 years ago or so.  I have
two partial bottles left.  No mold, no stink.  Still works (and smells)
exactly the same as it did when new.  I've never refrigerated it, just
kept it in whatever climate is inside my shop. 

Mike in Woodland