1. True Hollywood glamour, harking back to the days of the late 30's and the 40's (Nicole Kidmman, J-Lo, Sissy Spacek for example)
2. Decadence with an emphasis on body, even if it is UNattractive (McCartney's girlfriend, that Jennifer Campbell person)
3. Totally clueless, fashion victims to malevolent designers who prey on insecure stars ("Trust me darling, hiking the hem up in front reveals your best feature, your legs!")
I think J-Lo's dress tells you a lot about where the truly trendy are going. Although the color is not the best, the style is very retro-glam, and her hair is combed and arranged. It is very 40-s looking to me, as is Sissy Spacek's gown and Nicole's hair.
As an aside, why does Helen Hunt's hair ALWAYS look dirty?