Of course you would expect a designer to wear their own designs, but I have split them into 3 categories.
The Modifiers
Donatella Versace usually always wears something that has been modified from the runway, or especially designed, with at least one element of the design, incorporating something that has appeared on the runway.
Alberta Ferretti is much the same as Donatella, in that she takes an element of what has appeared on the runway, and modifies it to her own personal style.
Alberta does also occasionally wear clothes straight off the runway.
The Runway Regina's
Georgina Chapman wears nothing but Marchesa straight off the runway. The dresses are never modified, but she does wear the odd Chanel coat to spruce up a dress.
Georgina target audience is very much for women like her, attractive, wealthy, confident, successful, and glamourous.
The 6ft 4in former model L'Wren Scott, would be taller than most of her runway models, and I have mentioned many times that this designer should walk the runway herself, as she works her dresses better than any model - except Gisele - could.
Vera Wang is always in her own designs, and she always adds large necklace to everything she wears, which is very much her trademark.
Diane von Furstenberg designs for every woman, which is why she does not need modify her designs.
Stefano Gabanna was recently seen wearing this Steven McQueen t-shirt, which was seen on the runway for Spring 2008 collection.
The Pretenders
Kate Moss, who designs for high street retailer TopShop, will often wear her own collection.
The great thing about Kate is she can take a dress that cost £40, and make it look like it is off the runway.
Lauren Conrad rarely wears clothes from her collection, and from the above pictures you can see why. Unlike Kate's collection, I don't see many people embracing this line.