In those advertisements/infomercials where it's blindingly obvious that the person saying "WOW this is SO amazing! It changed my life! I would recommend this product to ANYBODY" isn't a regular customer, but a paid model reading a script, why do they not at least try to make them seem as genuine as possible?
Proactive be like
'Ughhh I remember on the Hollywood red carpet for my latest film premiere, I'd be so spotty and the tabloids would be zooming in my spots'
[CAMERA SHOWS UNFLATTERING PICTURES OF STAR'S ACNE]
'I wouldn't want to leave my house..'
[ZOOM IN CAMERA, EMOTIONAL RESPONSE]
'But thanks to Proactive I feel much more confident about my skin. Proactive is life!'
[CAMERA SHOWS STAR FLATTERING PICTURES, WITH SHINY, GLISTENING SKIN]
I think the main purpose of ads is to get their product into your head, so even if you don't particularly like the ad, they have made an impression on you and you know the product exists. When you go to the store later, the product will still be in your head and you'll know that it's available for you to buy.
Because people typically make purchases based on emotional reasons, not logical. Particularly with beauty products. We all know that the models are unrealistically attractive and the results seem too good to be true, but a primal part of us aspires to, and wants, it regardless.
But I would say that as someone who works in advertising, when you see an ad like that it's usually a result of an unimaginative and demanding client who wants product benefit spelt out in a literal way to justify the cost.