Take this photo for example. Before, you have some poor guy in a photo setup similar to a DMV. He's shot from above, to show his hair loss, and he's smiling but looks all angry that he's going bald. The "after" photo has him in the sun, smiling like he's playing football at the park, wearing a yellow shirt, and brimming with confidence.
I believe this is to distract you from the fact that he doesn't so much seemed to have gained any hair, but cut out the Eddie Munster widow's peak and made it slightly greasy with some gel hair product. In fact, I believe I could accomplish this look on a guy with a $4 jar of hair cream, and not the untold amount of money (really, it's hard for any of these places to tell you how much anything costs, and when you do, it's often OUR AMAZING PRODUCT IS ONLY twenty easy payments of $39.95!!!!! THAT'S LESS THAN A CUP OF COFFEE A DAY FOR A MONTH!!!!
Some go even further. The people in hair loss commercials also seem to lose weight in "after" photos. The funniest is the weight loss commercials where the "after 30 days" guy loses all his chest hair and becomes oily. What the hell did this Bow Flex do to him???
Maybe all the hair he lost goes to the Hair Club for Men for the weaves.