“American Idol” is back, and this clever marriage of “Major Bowes’ Amateur Hour” and “The Gong Show” appears to be as popular as ever. Because it is a competition involving judging, and because the results of the competition really do alter lives, the show inevitably raises ethical issues. In its very first episode, the fifth season of “American Idol” saw the show undermine a critical asset, its own integrity.

A hyperactive, barefoot, twitching and bouncing contestant named Dave Hoover sang in front of the judging troika of Simon Cowell (the nasty one), Randy Jackson (the jive-talking one), and Paula Abdul (the kind one). By any objective assessment, he was not up to professional standards, and that’s being diplomatic. Numerous auditioners who could obviously sing “Crazy Dave” under the table were unceremoniously dismissed, and not unjustly. Yet Abdul and Jackson, perhaps because they were punchy after so many wretched performances, perhaps to irritate Cowell, who correctly pronounced Hoover hopeless, but definitely because they thought it was a funny thing to do, actually voted him on to the next level of competition.

This isn’t earth-shattering, of course: Mr. Hoover will be good for a few more antic moments and then recede into William Hung Valhalla. But with this ill-considered decision, “American Idol” has given support to all its critics and detractors, including dismissed auditioners, who argue that that the competition is arbitrary, driven by considerations that have nothing to do with talent, or worse, fixed. All judging is to some extent subjective, but over five years the “American Idol” judges, especially Cowell, have shown that they can efficiently separate the gold from the silt. That fact is the bedrock of the show’s claim to legitimacy. Despite all the nonsense, the packaging, the publicity-seeking fools and the deluded would-be stars, the show does what it sets out to do: it finds and showcases the most talented singers. Once it is seen as intentionally choosing inferior performers for any reason, however, American Idol’s integrity is in jeopardy. And without integrity, the show is vastly diminished.

Last year, the Scoreboard designated a website called “Votefortheworst” an “Unethical Website of the Month” for its avowed purpose of distorting the “American Idol” competition by encouraging viewers to vote for the least talented singer. If the show’s judges intentionally “vote for the worst,” as Abdul and Jackson obviously did in Dave Hoover’s case, then the Scoreboard may have to reconsider its rebuke. It’s only TV, and only pop singing, and only a reality show, but the judges have jobs to do and people who care very much about the decisions they make. By breaching their professional duties and giving an inferior performer a chance that they had denied to hundreds of more serious and more talented competitors, the “American Idol” judges casually inflicted a deep wound to the show’s credibility and reputation for integrity. Such wounds seldom heal completely. Time will tell.