Style Showdown: Who Got it Right at Cannes

Sometimes stars get it right, and sometimes they need another celeb to step in and show 'em how it's done. Here's a look at some celebrity fashion hits and misses at Cannes and beyond:

Trend: Mermaid Skirt

Photos: Ian Wilson/WENN.com

Miss: The Fashion Spot has been celebrating Kirsten Dunst's style comeback at Cannes, and for the most part, her red carpet fashion has been on-point. Unfortunately, she flubbed with the gown she wore to the premiere of Melancholia, even if it is Rodarte. The criss-cross green wool bodice isn't bad, but the polka-dot and striped skirt is too busy and the mermaid hem doesn't fit-and-flare like the cut should, resulting in an unflattering baggy look.

Hit: Gwen Stefani's black mermaid-tail halter gown by L.A.M.B. Michael Angel looked fabulous on the red carpet at the Cinema Against AIDS Gala at Cannes. The gold belt adds the perfect glam touch and the dress stays close to her curves at the knee to create a stunning mermaid silhouette.

Trend: Corset Top

Photos: Andres Otero/WENN.com, Ian Wilson/WENN.com

Miss: Sofia Vergara recently became the face of CoverGirl, and for good reason—the Modern Family star is a stunner. But her bombshell figure was a little too va-va-voom in the suffocating corset top and pencil skirt she wore to the People En Español 50 Most Beautiful People event. The problem here is fit rather than fashion; her cleavage in the too-tight top is less than family-friendly, and we're not sure how she even walks in that hip-hugging skirt.

Hit: Rachel McAdams has made the hit list twice in a row! At the Sleeping Beauty premiere at Cannes, the actress showed that the underwear-as-outerwear trend can be stylishly pulled off in her 70s-inspired pantsuit by Monique Lhuillier. The sparkly golden bustier top fits her appropriately and looks sexy and chic balanced by the volume of her high-waisted beige trousers.

Trend: Sparkly Dress with Train

Photos: prommafia.com, stylebistro.com

Miss: Ke$ha may have blown away the crowd with her performance at the 2011 Billboard Music Awards, but her slate blue Jad Ghanour dress wasn't winning any awards. Ke$ha has said that she dresses like a "wild animal" and that might explain this jumbled look; the cut-outs cut in in an unflattering way, the bandage booties don't make sense with the dress, and the mesh train just piles another problem onto this strange outfit.

Hit: At the L'Oreal after party at Cannes, Cheryl Cole proved that wearing a sparkly dress with a train doesn't have to make you look like Trashy Bride Barbie. She shimmered in a daring long-sleeved gown by Roberto Cavalli, which featured a tiered mermaid train in contrasting silk and showed why the Fashion Spot recently profiled her bold personal style. The only thing that took away from the scintillating look was her mismatched red leather clutch.