The image is of a couple at sunset. Backs turned to the camera, with a brilliant sky. Doing well so far? Yes. But the image posted and getting "like" comments on a social networking page is bad. Bad, bad, bad. You can see "his" silhouette, or that of his head - and a blob affixed to his right shoulder. At first, I wondered, "What the heck is that? Is that a rock?" and then realized...it's his wife! Her head was leaning in towards his shoulder, bodies so close, there is no differentiation between him and her, hence, a blob.
Here is what you need to know. When you are shooting silhouettes, the viewer needs to discern who the outlines of each person in the photos is. The subject of the photo should be the PEOPLE you that are being photographed. The background is just that: a background.
Let me show you:
Here is another example, processed in HDR:
