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?
Living just north of the Golden Gate Bridge for an extreme example of cables. The cables on the bridge are constantly being painted due to the salt air, aside from that they are the same ones up there since 1937. Audio cables are not much different, as long as their sheilding and ends are kept protected whats inside should stay as good as new.
Used cables are good I have had some cheaper cables like monster and other discolor and the rubber jacket change for the worse or the little rubber bands around the connectors dry rot and fall off. But all my real cables like kimber, audioquest etc look as of they where new 10 year later.
Uru975, so what gauge are the G.G.B. cables? Can I get a pair of 1 meter cables cut from them :-)
Most cables usually get better over time. I have seen maybe the bare wire ends of a cable turn a little dark, but under the cable skin the cable was fine. I have never seen terminated cables deteriorate and I have an old M1000 Monster interconnect that is perhaps 15 years old and it's fine. Copper turns greenish and silver tarnishes, but only iron rusts, don't know of any audio cables made of iron.
My arteries rusted and went to hell since I
ventured past thirty-nine and my tubes went
from twelve gauge to slim threads, just like
my lamp-cord speaker wire I used forty years
ago. I am sure I can't sell them on the 'gon.
Thanks for the feed-back. Bgordon829