Stella McCartney was an early believer in the viability of faux leather in the designer market. For years, her endeavors in this area were mostly reserved for bags and shoes, but this time around she used the material – Skin-Free Skin, she calls it – for clothes, and it was surprisingly supple-looking on pieces like a clingy black twist-front top and a pair of caramel-colored trousers with the loose, relaxed fit of sweats.