Merry, you are very perceptive and it is good to keep a critical eye. These techniques, and others, are done constantly to con people out of their hard earned dollar. Unfortunately, I sometimes catch these in well respected journals also.
I remember, when John Vorhees, M.D. 's ( Chairman of the Dermatology department at Michigan ) article on Retin A and aging was published in the Archives Of Dermatology back in 1988. I oberved that the study patients smiled in the before picture and did not in the after picture. Of course, that would make Retin A's use look good. Since, Ortho, the maker of Retin A, had helped subsidize the study many who noticed this were critical. My own cynicism was tempered by the fact that Kligman, the developer of Retin A ( and Dove soap) had shown us residents, ten years before, that Retin A helped prevent wrinkles. I had the opportunity to use it on my patients for years before the article came out. My patients who faithfully used Retin A had skin which I thought ,subjectively, looked much better because of this. Thus, I believed Vorhees's findings.
My point is that you should be guarded when you analyze photographs (or data for that matter). But keep an open mind. As the saying goes: the proof is in the pudding. You try the product and then you draw your own conclusions. This is similar to any product. We dermatologists have been disappointed time and time again when medications do not live up to their billing. Skepticism is healthy.
While you might be on the mark regarding some of the photography tricks, legitmate, referreed, journals would not publish photographs which were "doctored" with airbrush or photoshopped.
If anybody cares to E Mail me, I will bring up another technique which can slant a study. I would rather not bring it up in this posting.