Hiya. Im a trained dermalogica skin therapist so cant comment on decleor but when u go to the show, you can be 'face mapped' by one of the derrmalogica representatives, they will look at your skin and discuss concerns with you and then recommend the right products for you, they'll give you a prescription sheet with these details on and then you can find your nearest skin centre to where you live and you can then purchase the genuine products from them. The previous poster was correct in saying they dont sell product at the shows but they do give you the correct recommendations and will discuss your skin in detail.
Hope that helps you.