Ads are made to sell, ok we all agree on that. But where are the limits in doing so ? A representation too far from reality would not have the risk to disappoint the client and break the dream patiently constructed ?
Ads vs. reality website compares burgers ads vs. real product shot just after having bought the "meal".
Like the traditional ads "before" and "after" for plastic surgery, Pundo 3000 is a very funny and recommended site which purpose is to show the ad, the pack then the real product "ready to eat". They also have published a book of the project that can be found here.
On top a nice example of perception vs. reality with the icon of Fast food : the Big Mac.