Of all the current British Royal Ladies I think Camilla has the very worst taste. Most of her hats are crazily oversized and do nothing to add to her overall effect.
Camilla's hats have been discussed at some lenght within the Group. Personally I feel that they are hugely variable in terms of style.
I tend to agree with you dmitri, that the oversized hats are the least successful and tend to create the effect that they are wearing her, as opposed to she wearing them!
Still hats must stil be somewhat of a novelty in her working wardrobe, so perhaps it will take some time for her to get a good sense of what suits and is appropriate for her age, status and the function for which any particular hat is needed...........?