[fumblebee]

wouldn't "useful ad" imply either 1) clicking through and buying the product or service, or else 2) building up a positive brand association to help increase sales later?

remembering an advert correlates but is different to it being valuable.

[svachalek]

Yeah I remember some studies showed this with overly sexy ads. They were very memorable to the audience but all they remembered was hot chicks, they couldn't recall the product.