Perhaps the only thing worse than being an unknown, struggling musician without a hit song is actually scoring that hit and coping with the sudden, unfathomable fame that goes along with it. Just ask Kurt Cobain -- or Warren Zevon, who performs Sunday, August 5, at the Fox Theatre. After a meteoric spike in his popularity with the whimsical "Werewolves of London" in the late '70s, Zevon's star leveled and then dropped considerably -- but not before he made the obligatory rounds as Wasted Superstar Guy. His ongoing experiments with monumental liver destruction, and his stamina, are legendary; Zevon is good friends with Hunter Thompson, which requires vast reserves of energy in itself. (Or maybe the good Doctor has been providing Zevon with some weird voodoo medicine that has kept him going all these years.) Zevon has been off the map in terms of real popular success since the "Werewolves" period, but the way he continues to write relevant, soulful songs makes it seem that he isn't really interested in all that fanfare, anyway. The songs on his recent Life'll Kill Ya reflect the polarized touchstones he is known for: acerbic wit and mournful, endearing sentiment that would sound maudlin coming from anyone else. Zevon has led a life that would break lesser humans: He is a paragon of strength, a beast among men. Like he says: "I'll sleep when I'm dead."