Timoteo said:
For that particular dress, which has a cut-out for cleavage, big titties are necessary to really work it right. Katy gets the W for this one. Also, I can't say Perry's face is BUSTED, even without makeup.
Katy Perry has big eyes, big lips, and good symmetry. She's got a very expressive face. She's also got a large forehead, prominent chin, and a fairly wide jawline that misses being a manjaw but doesn't remotely compare to Bingbing Li's delicate feminine lines. In other words, her face is a good surface for makeup. 6.5 without makeup, 7-9 with makeup. She's a lot like fashion supermodels in that way, except with less structural perfection and more expressiveness (perfect for music videos).
She has a fairly large frame and lacks amazing svelte curves or toned athletic shapeliness (eg Aryane Steinkopf), but she does have huge tits and a good waist-hip ratio. And while her proportions aren't perfect they are adequate. This means she can get a lot of mileage out of dresses like the one in the picture.
Katy Perry is best admired from afar. But I would definitely bang her given the chance, especially if she was wearing a dress like that. But Bingbing Li is more naturally beautiful.