For me, the appeal is different. I like to look for the misfits, the imperfectly evil, the ineptly evil, the secretly good, the illegitimate or accidental or unexpected offspring, that sort of thing. Always Chaotic Evil is okay as plot filler, but not really as interesting as the exceptions. Some good examples may be found in my poetic series Sort Of Heroes. Brod is a troll, introduced at the beginning with his friend Nib. Later on we also meet the quarter-orc Hicket. I have a half-orc healer simmering in the back of my mind too.
Of course, since this author mentioned the idea, but did not actually write it, I'm seriously tempted to create something along these lines:
Inspired by varied African folklore, they’re definitively not Orcs–nor are they based on any existing human phenotypic differences. No “tall, broad-chested, sharp-nosed, pale-skinned, with thin mouths and blue eyes degraded and repulsive versions of the (to POC) least lovely Caucasian-types” in my stories…cuz that would be ridiculous.
I don't think it would be ridiculous, I think it would be awesome, especially with handsome and dashing heroes of color. Caucasian body type doesn't get mocked enough. I was deeply amused to discover that my Tingo, who are anthropomorphic canids, describe Caucasian humans as "the Grub Ones." Because they look like larvae with their pale skin.
Conversely I'm intrigued by creatures that are expected to be good, but aren't, or aren't entirely so. Angels who are into naughty sex, or who smoke, or corrupt the innocent. Paladins gone awry, like Johan attempting to bail out of service; or paladins of evil, like Bodil. One of my very early creations was a violent and raunchy red unicorn.
Expect the unexpected. Look for patterns in literature, smash them with a sledgehammer, and decoupage the pieces.
EDIT 6/24/12: Inspired by a prompt from marina_bonomi, I have written a poem featuring demons with Caucasian-type features. "A Hole in the Blanket" tells about a young warrior whose little brother is stolen by demons, and she is determined to get him back. marina_bonomi has expressed interest in opening this for microfunding, so you can watch for it to appear later. 138 lines, Buy It Now = $69