I have finally completed my paper “Three revealing experiments in music genre recognition”, submitted to ISMIR 2012, which formalizes my results here, here, here, here, here, and here. I make available here the attendant code for reproducing all experiments and figures.
My one line summary of my work is:
Two of the most accurate systems for automatically recognizing music genre are not recognizing music genre, but something else.
That something else is the subject of further work, not to mention replicating and testing other systems — starting with this curious work.
Thank you to all commentators and test participants!