I've done this occasionally. But really, how advertising works is it builds up demand by repeated exposure. The rule of thumb is that it takes somewhere around

I've done this occasionally. But really, how advertising works is it builds up demand by repeated exposure. The rule of thumb is that it takes somewhere around 7 interactions, on average, before somebody makes a decision to purchase. You want proof that advertising works? Facebook's revenues last year were $85 Billion, mostly from advertising. And it's growing every year. Merchants wouldn't be spending that kind of money over a sustained period if they were seeing negative ROI on their ad spend.