Even before Aerosmith frontman Steven Tyler and pop star Jennifer Lopez revealed they would not be back for the 12th season of "American Idol," rumors started circulating that Hollywood bad boy Charlie Sheen was being considered as a judge on the show.  In an interview with TMZ, Sheen noted that he would only join the singing competition show if FX, the home of his new sitcom, signed off on a deal, and if his salary were "substantial enough" that 20 percent would be matched and donated to his favorite charities by the show's producers.