To be honest, I usually do not click on ads before I make any purchase in any of those e-commerce: I usually just made up my mind about what I really need and purchase it by searching and checking it out on amazonm; I would just ignore most of the other forms of ads that are constantly shown to me.
However, before I reach my mental maturity, I did click on a bunch of ads for online browser games. They always show up with extremely loud background music to grab your attention, then use the method of false advertisement: presenting you with contents/video clips of gameplays that are not in the actual game itself.
As the stupid ten to twelve-year-old boy, I always fall for that kind of false advertisement. I guess the trick for their craft is to immediately track your attention with the loud blast of sounds(like what people do with babies), and then presents a genre of browser game I have recently and frequently played on their flash game websites(Interests of the viewer), which claims to have insanely good graphics or intriguing game mechanics. They did it by showing a video clip of the game play/cgi of another popular game at that time: starcraft, warcraft or some popular games from PS 2, mainly because I used to own one together with my brother.
But since then, I felt I have lost my trust for the majority of online advertisement, both for products and services, fearing they might just fail my expectation and leave me with shame and disappointment before I close their site.