They are not the outcome of randomly placed features as is the Man in the Moon and the 'face' on Mars, etc. Their 'recognition' is based on cues provided in carefully crafted artwork. See for example the manipulation which took place to the features of the moon's surface to present a more 'meaningful' image of a 'man on the moon' in a Marlboro Ultra cigarette ad from Germany. I t requires very few basic features to recognize a face as is indicated on the Faces page. Nor does it require a great many features to introduce the word Sex or any of the other images noted on this site.
People are remarkably good at identifying objects on the basis of limited cues.
And we learn to make the most of limited information. Artists, cartoonists and others are acknowledged as experts at providing viewers with the necessary cues. In most cases such presentations are overt and one can but wonder at the skill of the cartoonist or caricaturist in conveying meaningful representations using a few lines. In adverts, however, artists create images that are often on the borderline of perceptual ability. In such cases, one can only wonder at the depth to which some commercial organizations sink in their search for profitability.