There's no denying the guilty-pleasure appeal of American Idol but this clip reel of highlights and lowlights underscores how fleeting and watercooler-driven it is. Okay, it's a little bit fun to revisit Kelly Clarkson's and Clay Aiken's style-challenged beginnings before the dye job and straightening iron and to reminisce about Justin Guarini as a heartthrob on the upswing. Beyond that, though, not enough time has passed to make The Best & Worst of American Idol: Seasons 1-4 a nostalgia trip worth taking. And now that William Hung has proven there can be too much of a bad thing, those ap-pawl-ling ''worst of'' auditions should never have resurfaced after serving as the requisite warm-up each season. EXTRAS As for the interview footage, let's just say we'd rather hear the contestants sing than talk. (Clarkson: ''Waitressing isn't the funnest job in the world.'') And Paula's backstage chats with season 4's finalists on their Idol concert tour does nothing for Carrie Underwood & Co.'s street cred. Shocking revelation: They often didn't have time to pray together before the show!