Rolling Stones musician Keith Richards has risked upsetting the heavy metal community by revealing he can?t take Metallica and Black Sabbath seriously. The guitarist is not a fan of heavy rock and he cannot understand the appeal of the genre?s top acts. He tells the New York Daily News, ?(Rock music) sounds like a dull thud to me. It?s endless thudding away, with no bounce, no lift, no syncopation.? Richards? disdain for musical genres also extends to hip-hop, with Richards insisting he feels the music has little substance.