There are 2 problems that I see with the test. 1 is the coat hanger is probably the same gauge as the monster cable. Gauge is the main cause for a cable to sound good or bad. 2 the coat hanger is a shorter length which would have lowered the resistance.
With all that said any 12 gauge wire is good for serious listening (high end home theaters and listening rooms) and for general listening (listening to background music) 16 gauge is perfect.
From my experience all the oxygen free wire does over the non-oxygen free wire is it doesn't turn green as fast.