I remember when I was a little kid (late 70s or early 80s) at a CA they had a huge part on bad music. This was during the backward masking heyday. I remember them playing a song - I think it was "Another one bites the dust" by Queen. Supposedly, it was backmasked to say something like "decide to smoke marijuana". They played it backward at normal speed, and even when they planted the suggestion, no one could make it out. Then they slowed it down real slow and it sort of sounded that way. But, since the mind was looking for the pattern, you wanted to hear it. The crowd ate it up but I thought it was kind of creepy.
Of course, after the program, the lynch mob was in full effect.
I could understand the whole metal thing in some respect but never got the obsession with hating rap. Not all rap was questionable, even by JW standards, but it seemed that was the most vilified type of music.