I don’t get the Carol Bayer Sager newsletter anymore, so I missed when exactly she turned into Joan Collins. But there she was on “American Idol” last night, in all her Liz-Taylor-fright-wig glory.

There was no good reason to have her on “Idol” as a guest judge, since she brought just slightly more to the show than Jewel did last week, which was less than nothing. The show doesn’t need guest judges at all. Just keep giving viewers the three ingredients we watch for: good singers, horrible singers, and cutting remarks from Simon (with a dash of “dawg” from Randy and a splash of whatever Paula’s drinking). That’s the formula, and no fourth chair is necessary.