Buying used old cables

Is there a life-expectancy of old cables? Old cables
can oxidize (rust) and get brittle. Thus, lose their
conductivity. I have old Monster speaker cable in my
storage area which shows darkened, discolored wire. Is
it still useful? Mobility, relocating, moving, bending,
manipulating, as well as aging must have negative
consequences on any cable. Should we consider this in
our purchase of "used" cable thinking we are getting a
good deal?