The answer is quite simple.
In order to make muscles look more defined, a dark than can help. But an all over tan will also reveal areas that don't look so good. So you should only lightly tan the parts that you do want to draw attention to.
Another techinque is to use baby oil for the same effect. Baby oil increases the effects of sunlight, so can help you get a tan much faster. But be warned, it also severely increases the risk of sunburn and skin damage.
Professional bodybuilders will use either technique before a major competition or a photoshot. But they are not usually dumb enough to attempt BOTH. With Stephanie mis-interpreting bad advice from both her husband and father, the results are as above.