06/15/2012 10:21 am ET | Updated Oct 11, 2012

Rihanna, Katy Perry And 11 More Worst-Dressed Celebrities Of The Week (PHOTOS)

Sometimes perfectly fashionable stars come down with a case of style amnesia, where they forget that teased hair and slits-up-to-there do not make for a best-dressed look.

There are also cases of ill-fitting garments that droop, sag and pool in all the wrong places. Ladies, get yourselves to the tailor!

Here, 13 stars whose fashion flops are a lesson in how not to dress. Then check out our picks for best-dressed stars this week for some wardrobe inspiration.

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Worst-Dressed Celebrities Of The Week