I see what you mean and stand corrected; I wasn't assuming the case where the product sells without advertising at all.
From a gut feeling I can say that the customer came from some result of previous advertising (as we're talking about products like sodas not life-essentials like oxygen), but I guess there's no way to know since those previous ads being tv/print ads were not tracked.
If we suddenly stopped all other forms of advertising and only used online ads, in 10-20 years each customer can be tracked exactly to what ad created the first impression about the brand and thus be more accurate (still excepting marketing like word of mouth though)
From a gut feeling I can say that the customer came from some result of previous advertising (as we're talking about products like sodas not life-essentials like oxygen), but I guess there's no way to know since those previous ads being tv/print ads were not tracked.
If we suddenly stopped all other forms of advertising and only used online ads, in 10-20 years each customer can be tracked exactly to what ad created the first impression about the brand and thus be more accurate (still excepting marketing like word of mouth though)