It is an entirely fictitious occupation invented because, in our glorious age of multimedia, it's no longer enough for someone to be good at indulging one of the buying public's senses. Sure, Rosie Huntington-Whiteley looks amazing in the latest Burberry Body campaign but apparently that's not enough. She must use her words (none of which should be "paycheque") to express her enthusiasm for Burberry.
Anyone who has kept an eye on the reviews of her Transformers: Dark of the Moon performance will know that this is a risky strategy. Not since the Austin Powers movies have I heard the word "fembot" being used so freely. So why is it important that she lend her voice - or at least her sub-edited sound bites - to Burberry's fragrance campaign?
It's because of the cult of celebrity. If they endorse it, we will spend.
Of course, it's not like this is particularly new. Testimonials, whether from regular customers or famous faces, are a commonplace form of advertising and having a public figure chatting about how awesome your products are in every interview they grant is unlikely to do your brand any harm but there's a hollowness running through a lot of these famous-faced endorsements.
Armani's press release regarding Rihanna working with the brand was even more overt: "Rihanna will be the new global testimonial for Emporio Armani Underwear and Armani Jeans from autumn/winter 2011-12." RiRi isn't billed as the face or the body of the lines - she has become very embodiment of a testimonial.
But - and this is the problem - when it comes to fashion, isn't the testimonial meaningless? The product is the garment and it will fit everyone differently and flatter some and not others. Rihanna and Rosie may well love Armani and Burberry (probably without having to part with the cash we mortals would have to stump up) but they are phenomenally good looking women. Of course they look gorgeous in the clothes - and the clothes look gorgeous on them.
What relevance do either of their fashion choices have to me, a woman of completely different height, colouring and proportion?