'American Idol' Guest Judges: We Grade Katy Perry, Joe Jonas And More

Could any of the fill-ins replace Simon, or should they never be asked back? Our 'Idol' expert takes a closer look.

With [artist id="1397"]Paula Abdul[/artist] moving on to bigger and better things (TBD), "American Idol" had a gaping hole to fill during their season-nine audition process. As a solution, producers put their Rolodexes to good use and called up some celeb pals to sit in during the tryouts.

Everyone from Broadway vet Kristin Chenoweth to heartthrob Joe Jonas answered the call. But how did the various Rent-A-Judges stack up against one another? Which ones floundered and which ones made the grade?

It's time to rate the "American Idol" guest judges!

[artist id="3274550"]Katy Perry:[/artist] A+

Katy was filter-free, and we loved her for it. When she didn't like the contestants, she told them so. And when she noticed Kara DioGuardi judging contestants based on their depressing life situations instead of their singing ability, Katy called her out on national television: "This is not a Lifetime movie, sweetheart." Truer words have never been spoken. Actually, that's false. "Katy Perry should replace Simon next season." There. Now truer words have never been spoken.

[artist id="854"]Mary J. Blige:[/artist] A-

Mary had the audacity to laugh in contestants' faces and disagree with the other judges. While we wouldn't want her to replace Paula indefinitely, her diva attitude helped give the Atlanta auditions a neat "what-will-she-do-next" edge. If only she looked like she wanted to be there. On second thought, that made her appearance even more compelling.

Neil Patrick Harris: A-

Neil Patrick Harris had a winning mix of Paula's kindhearted sensitivity and Simon's razor-sharp wit. (Our fave NPH quip was this response to a dominatrix who revealed she was on "Barney and Friends" as a child: "I knew I recognized you!") In fact, Neil may have been too similar to Simon. How else to explain the tension between the two judges? Extra points to NPH for not flinching when he was on the receiving end of the Cowell Scowl!

[artist id="50102"]Shania Twain:[/artist] B+

Shania has been out of the spotlight these past few years, but once we got over the "why is she there?" factor, we appreciated Ms. Twain's voice of compassion, which now had a vaguely Midwestern accent! (Perhaps an ode to Chicago, the city she was critiquing?) Plus, Shania provided an instant-classic "Idol" audition moment when she told Asian stud-muffin John Park that he had a "nice bottom end." Hello!

Kristin Chenoweth: C+

We had high hopes for the pint-size Broadway superstar (who you may remember from "Pushing Daisies" and "Glee"). Alas, Kristin only hung around for half the Orlando auditions and her girly sensibilities encouraged DioGuardi to be even more annoying than usual.

Victoria Beckham: C-

Posh Spice seems like a very nice robot, but wow, Suri Cruise could have provided more in-depth critiques of the auditioning hopefuls in Boston. (Victoria will be back Tuesday for the Denver episode. Perhaps she'll redeem herself? We think "zig-a-zig-NOT.")

[artist id="1228637"]Avril Lavigne:[/artist] D+

The Canadian "punk" rocker was awkward, fidgety and obviously more invested in her devil hoodie than the singers in front of her. The one "insight" Avril brought to the table was that successful musicians can't be married with children. What?!

Joe Jonas: F

If he didn't put any effort into his "Idol" appearance, we're not going to put any effort into reviewing it. No wonder producers kept the day-two segments of Dallas noticeably brief.

Who did you think were the best and worst guest judges? Did you miss Paula? And who would you put on a short list for Simon's replacement, if anyone? Leave a comment below.

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