I haven't heard much about cable burn in, a lot of people seem to believe in it though, but without proper proof. The idea that cables to oxidize in the duration of their life can push the idea that cables can burn in. Oxidation can lower the radius of the actual metal the electrical signal has to travel through which means increased resistance. This increased resistance means a possible change of sound. My question is, is this increased resistance enough on its own, or is there something else going on?
With many aftermarket cables on the market the oxidation is only changing the metal used for plating, and not the actual conductive material itself. So the effect in such a case would be placebo, and not a perceivable one.