as long as she keeps her wits and isnt bullied into anything it might be a bit if fun...you can always take pics of her instead
many photographers studios do this...offer a free photography session...only to charge for the photos...
i was offered it by an old pal once, and after discussion took her up on it, with the belief that she would get some interesting shots for her website and id get one or 2 nice pics...she was a con too though...