During this performance of Waking Up In Vegas (from the album One Of The Boys) on American Idol TV show, Katy Perry was wearing an Elvis-style cape with Adam Lambert written on the back. He was one of the best contestant of this competition in 2009. But as she was probably expecting, people talked a lot about this cape. This was the first time a guest artist has openly campaigned for a contestant on the show.
As she endorsed it during the American Idol results part of the show, some of them said that it could have really affected the votings.
Even though that's not such a big deal, many thought that Katy Perry was wrong to do so, pretexting that was unfair. They said that it will be hard for anyone to believe that her act wasn't orchestrated.
Everyone has different opinions. Also, others were glad seeing that Katy Perry isn't an ordinary artist : she's different because she's herself with her outrageous style, and doesn't follow or cares the rules. Also, for them, it was cool that she wore his name on her cape.
Anyway, although Katy Perry seemed to be rooting for Adam Lambert and that he didn't seem needing any help, he finally didn't win, and Kris Allen did.