I think it would probably be wide eyed, almost manic looking. If it were a fragrance expert it would almost certainly look like it had slept in it's clothes.
Personality wise I suggest a friendly, warm and yet insincere manner.
But the most important factor is it is able to give the most generous descriptions to the most humble of products. An exaggeration mode or, dare I say it, untruth mode, is vital.
And it must not ever, ever, EVER mention P+P. If it tries the computer will close it down.
Oh, and they must have completely and utterly failed in their chosen career path (Cruise Liner entertainer, Butlins Red Coat, Electrician, Sound Engineer, Actor, Singer, selling perfume in Debenhams or in extreme cases simply became way, way too old and dare I say scary to be a children's television star).