Critics have described his singing as less than kind, but "American Idol" reject William Hung (search) says he wants to play only good-guys in his fledgling acting career.

In Singapore to promote his first film, the action-comedy "Where is Mama's Boy? (search)," the Hong Kong-born Hung ruled out any nasty roles.

"I would like to preserve a good image and not play the bad guy or do anything that's obscene," Hung was quoted by The Straits Times newspaper as telling a news conference.

Hung stars in the Cantonese-language film, opening Thursday in Singapore, playing a street vendor who befriends a music club owner played by Hong Kong starlet Nancy Sit.

Hung shot to fame in the United States in a bungled but earnest audition for the U.S. talent show "American Idol." The 21-year-old won legions of fans by telling the judges he did his best and had no regrets about being panned for his nerdy, out-of-tune rendition of Ricky Martin's (search) "She Bangs."

Hung, who studies in California, later released an unlikely hit album "Inspiration" that has sold more than 100,000 copies.