User blog:Vanakita/What makes a good original vocaloid design?

I've been going through entries from the previous vocaloid design contests and this question popped in my head. From all the entries I have seen, the ones rejected are either


 * stereotypical by concept standards


 * stereotypical by vocaloid "standards"


 * too detailed


 * over the top


 * or simply too bland.

What is, in your opinion, the something that makes an original vocaloid design good and well-accepted?