What makes an image stick in your mind

Like this Rolling Stone cover of John Lennon and Yoko Ono

I've been noticing the use of black in the ads/posters I've been talking about and am interested in using it for my print ads as well. Before now, I hadn't considered using it on a model to contrast with the environment, but vice versa. This image sticks in my mind because of not only color contrast, but the playfulness and vulnerability of gender. We're accustomed to seeing women naked, or near naked, in print, but here Yoko Ono is fully clothed. That's why I want to play with gender in my Time ad, since many men are traditionally thought of as the traveling business person.