I have noticed a fair amount of corrosion as my cables have exposed wire (in a high humidity environment) so I would advise you to check on the condition of the terminations. Also, check on the condition of the sleeve or outer sheath which could be symptomatic of damage to the wire.
Do speaker wires degrade over time ?
I am looking buying a pair of used speaker cables from the 80's. I have no idea if there is a life expectancy on cables. They are probably broken in !