Comment by mapontosevenths

> I wonder if a combination of all of those may work for a subset of songs, but I don't think you can do it with any confidence :(

Thats a solid point. Pretty much all of my ideas are probabilistic. I suspect you're right and it will have to work a bit like spam detection, where each "fail" for a test is seen as one indicator that adds to a score. Then above a threshold score it's flagged for further review and sent to a "spam" folder where a human can judge.