Simon Cowell has never minced words, but he seems to be keeping relatively mum (as in, outright BSing) when it comes to LeAnn Rimes' 'X Factor' performance.

For those of you not keeping score, Rimes performed with then-frontrunner Carly Rose Sonenclar, 13, on the final performance episode of the Fox show. And Rimes, uh, blew it.

Rimes was unintelligible, flubbed the lyrics and was often off-pitch. Was she having mic and monitor issues? Maybe. But according to reports from backstage, where Rimes was also rumored to be clumsier than usual, it sounds like she had a liquid or chemical sabotage to her vocals.

Still, Cowell was diplomatic. He called Rimes' performance "interesting," and when asked if the homewrecker and hot mess was drunk or high, he grinned, "No ... she was happy!"

Meanwhile, Sonenclar's parents are royally pissed at Rimes for implying that it was their daughter's fault that she sucked. TMZ said Rimes was just upset that Sonenclar sang circles around her.

We don't think it's those circles that made her dizzy and disoriented.