Fashion bloggers day to day post about new clothing lines, cool accesories, new brands, about designers, runways, trends, etc. Letting the blog reader appreciate the brand or designer shown on the blog; and for instance, keeping that information for future buying. Blog readers tend to believe more in a blog, than a magazine ad, or t.v. ... So brands get all the advertising without paying a penny.
So what brands should do is focus their attention in bloggers, and find the most popular ones, or the ones that reach their target market, and contact them, show their products, give them some samples, and the blogger will most likely post about it, and a really big audience will see it and will make an impact on them and the brand.
So, if you want to give me some samples, I'll post for sure about them ;)