Alejandro Aranda has been wowing them on “American Idol” since March 6. He says he’s a dishwasher from Pomona, a description that, combined with his humble manner and way with an acoustic ballad, have made him a sensation. I delve into his recent past as an open mic and street performer in Pomona and Claremont in Sunday’s column. Photo from March 30 Pomona appearance by Liliana Pardo.