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Katy Perry

Pop tart Katy Perry left little to the imagination in a sheer ensemble while out and about in Paris on Thursday. While we adore her coral-colored Jimmy Choo handbag and strappy Christian Louboutin sandals, we abhor her tired blue tresses and minty Vera Wang mess of a dress. Oh, and those granny panties ... they belong under sweatpants, not on display during Fashion Week!

What Were They Thinking?!

This week's worst-dressed stars include Katy Perry, Rihanna, and Vanessa Hudgens.