The Primary purpose of advertising is to sell the product. All other aspects are strictly subordinate to this primary purpose - including providing information. If Dis-information serves this primary purpose, it will be used. That is why there are so many (non-profit) organizations devoted to such subjects as labelling laws and "Truth in Advertising".
<...but its hardly the only, nor even the major means of creating awareness.>
I don't know of studies revealing the truth of this contention when it comes to product purchasing. Certainly companies that spend hundreds of millions of dollars on "promotion" including motivational research on human behavior, unconscious triggers, impulse buying, etc. seem to think it worth the effort.
It is obvious that appeals are made to the non-rational. Were our consumer economy to be driven by pure "information" it would collapse.
McSpotlight: Quite correct. This is why we believe that advertising aimed at children under ten is particularly pernicious; the children are old enough to get the gut-level message ("buy Brand X") but not old enough to apply some critical judgement to their perception; furthermore, children are aware that they can often coerce their parents into doing what they (the children) want - advertising that plays into this known effect ("pester power") is irresponsible in our view.