Why it shouldn't work
The spell Sculpt Corpse also say:
You can make the corpse one size larger or smaller and change anything else about it including its apparent type, gender or age.
You may argue that a juvenile dragon would be more or less the same body volume than a full grown adult (or at least within one size category of said deceased person), but you'll need a bigger corpse to create a bigger dragon.
The part above is not a limitation in itself, so I'd add:
This spell merely changes the appearance of the corpse.
The change is only cosmetic. When you skin that poor cow-looking-human/dragon-looking-human, you will have human skin that looks like leather. It won't possess any of the special properties you want to give it.1
So it's gross, potentially useless unless you manage to sell it to an unsuspecting merchant who won't notice the trickery.
Why I wouldn't allow it to work
Basically, it would be way overpowered.
A dragonhide armor costs twice as much as a masterwork armor of the same size and type (and give discounts on energy resistance enhancement according to the dragon's type if it had one).
A dragon provides enough hide for a masterwork hide armor for a creature one size smaller. Meaning, each time you would kill a human and turn it for hide, you would gain twice the price of a small masterwork hide armor (330 gold total). For casting a first level spell without a cost in component.
If the spell worked that way, every first year magic student would run the countryside to buy cartloads of corpses of whatever creature they can get their hands on and flood the market with dragonhide. And Angelskin. Or any skin that has any value (and therefore, wouldn't have any afterwards, cause you now have near infinite supply of the stuff).
If a player was allowed to do so, expect a major increase in income. Go buy a wand of Sculpt Corpse (750 gp) and slay some 50 helpless Medium creatures, you will get your money worth (16 500 gp).
TLDR: Bad idea, should not work by RAW, should not be allowed if you care about the consistency of the setting you're playing.
1: Can't prononce on the difference in quality between human and cow leather, although I surmise human skin won't be nowhere near as thick and tough.