  Apparantly what this ad is trying to lead the consumer to believe is that their product will give you so unbelievably beautiful skin (and help you become really attractive) that you'll be comfortable showing it off to the world. At first I got the impression that they were trying to tell you that their soap gives you the awesome feeling that this woman seems to be experiencing, but I hope they'd give us consumers more credit then to believe that. That, and the whole "Zest Spring Burst" part of the ad is all but invisible in the ad's graphics. What you see here at first sight is an attractive model in an ad, covering her breasts in an attempt to convey to the audience that by using their product, you can be just as sexy.
I don't know about that though. Obviously, we as humans aren't dumb enough to fall for that. What this ad's really doing, is getting your attention with the naked woman. Once it has your attention, it doesn't matter what you think about the product at that time, because once you hit the store, and you're looking for bath soap, Zest will be one of the brands in your mind, as you were attracted to their ad in the magazine by their naked woman. It doesn't really matter if you ever intended to purchase their product. It's a better marketing strategy then most might think. Check out Geico for example. Their commercials SUCK!! but their company name is easily remembered because of their SUCKY lame commercials.
I guess in this example you gave us, they did their job of hitting their target audience. Who reads Rolling Stone? In my opinion, mostly younger men who like to see naked or half-naked women. There are also younger women who read the magazine, and they're just as likely to be grabbed by that ad as any man, as it's a very visually attention getting display. 
