How many times do you think you might get it right (on average) if you were purely guessing. What do you think the possible test to test variation on that might be?
Also - the listener response was always "off" which suggests you were not hearing any difference at all.
Respectfully, we will have to agree to disagree on the usefulness of this test.
I for one would not take these odds as to whether or not the chamber of a gun pointed at my head was loaded, but for something as life critical as audio, I think this is a valid data point if not a definitive result.