It's very hard to explain about assets because some 3D assets just have "it" and others "don't have it" no matter how technically astute the author might be. Sort of like Bowfinger was explaining to that actor who auditioned for his movie.
For example. Rolfy's zombies just have "it." Kravenwolf and Strelok have "it," too. Other assets just don't have "it." They may have the scale, proportions and shape correct but they just suck. I cannot explain it. They don't look good no matter how you light them or present them.
I recommend all aspiring TGC developers take a long good look at people like Bond1, Simon Benge, Strelok, Cheesecake, Kravenwolf and Cyborg ART's pipes before you put your stuff up for sale. Does your stuff have "it?" If not, maybe you should work on it some more before putting it up on the store. Sometimes a different color scheme or texturing will do it. I have gotten assets off TGC, retextured them and they instantly looked much better. So work hard to give your products "it" and you will get far more sales. If somebody is browsing the TGC store they will always see that "it" products leap out at their eyes when they see them and suddenly compel them to reach for their credit card. It's the difference between selling a few assets and a lot of assets on TGC.
The best game to work on is the one you enjoy playing the most.