Liszt had warts in later life.
This is from the same site.
Were the seeds of Heavy Metal planted by Franz Liszt? Liszt was the ultimate experimenter of his era, much like Leonardo Da Vinci. They analyzed, formulated and recorded brilliant and visionary ideas that far exceeded the limited scope of their own generation. Thus, they both fell prey to suspect and even ridicule by some of their contemporaries, being called dreamers or worse. Only the more astute could realize that the being before them was of a celestial, higher order - the ultimate genius, misunderstood by the masses.
Liszt brought to music unprecedented emotional and psychological impact that previously never existed, paving the way for *Wagner, Tchaikovsky, Puccini and others that followed. Though Beethoven previously touched upon a heavier style with the Coriolan Overture, or Mozart with Don Giovanni, or even Boccherini's La casa del Diavolo, they never delved as deep into the brutal dark side of Man, or the devil, as did Liszt. Liszt wasn't afraid to invent menacing harmonies, of diabolical and dissonant proportions
