In my book American Idolatry: Celebrity, Commodity and Reality Television, one of the theories I propose is that there is an inversely proportional relationship between female physical attractiveness and the odds of a contestant winning the entire competition - the "hawter" a female contestant, the less likely it is that she will win. In fact, any female contestant labeled early on as "sexy" is essentially doomed.
The term "hawt" is used purposively here in a "trololo," internet meme-y fashion. One of the truisms of American Idol is that an unattractive woman will never get near the top twelve. Even those outside of the traditional Western conception of beauty - Mandisa Hunley, for example, or Crystal Bowersox - are by no means unattractive. But "hawtness" - that is, a stereotypical adherence to male fantasy perceptions of attractiveness - is a step above "attractive." This Carrie Underwood is "attractive;" this Carrie Underwood is "hawt" (Underwood won, in part, because her farmgirl-next-door persona was somewhat played up by the program to avoid hawtness).
Hawtness is, paradoxically, both encouraged and punished in the Idol context. For example, Simon Cowell once famously instructed S6's Haley Scarnato to "wear the least amount of clothes as possible. Because, look I’ll be honest with you, you can’t do well in this competition based on your voice because there are much better singers." This becomes the Sword of Damocles hanging above the head of the hawt contestant: eventually, no matter who she is, the criticism will turn from her voice to her looks, and those looks will be the petard upon which she is hoisted. Eventually (or, in the case of someone like Megan Corkrey, almost immediately) the conversation will end up in a place where the contestant only achieved her position because of how she looks rather than the quality of her voice. The latest victims - Pia Toscano and, especially, Haley Reinhart - stood no chance of winning. The concept of a powerful, sexual woman creates cognitive dissonance in Western culture and must either be rationalized or rejected. Either the powerful, sexual woman is a bitch/whore or she is outright rejected so we don't have to think too hard about her. Or both.
"Haley is good, but she dresses like a slut, so that must be why people are voting for her, so I am not voting for her and I hope she gets voted out."