I think Dexter could do his double biceps better. If he could contract his abs instead of having them bulge then he would place higher. Even a vacuum would be better than the weird abdomen look.
Other than calves (which is I think is a major detraction), the only thing that Dexter lacks is that three-dimensional look to the upper body. I think he ought to work on doing a vacuum when he poses to help lift his ribcage up.
Also, in his back poses, he should place his thumbs outside his fingers, clenching the fist in the usual way. Some bodybuilders have this weird habit of placing the thumb between the index and middle fingers. Dexter is guilty of that and I think it tends to draw a bit too much attention to the delts. A rear double-biceps shot ought to have a seamless flow between the shoulders and the back. In Dexter's case, the shoulders tend to pop out a bit too much and I think the way he holds his fingers exacerbates this.
The thing about this classical posing detail is that it creates interesting illusions with the physique. Competitors ought to be rewarded somehow for being able to understand how to present their phsyiques in the best manner. In that way, you wouldn't have them looking, as mentioned in a previous post, like a third grader mocking bodybuilders and the way they stand.