I really liked what Mouseforatu did with the half-orcs in the Advanced Player's Guide. They descended from neanderthal/proto-human and orc interbreeding. So they're a true breeding race with old ancestry.IMHO I think the main problem with half-orcs, fluff-wise, is the assumption that the 'half' part means 'human'.
Aye. I do similar. In fact, I think Half-Elves make great changelings (in the original sense of the word, not the doppelganger guys).In my game I've done that with half-elves. They're called 'half-elves' colloquially, but really they're half (or just part) fey.
I offer Tiefling Houses. You have some that look the way they do in the book. Then you have the goat-legged ones with ram horns. Then you have the red-skinned ones with spade-tipped tails. All dependent upon lineage.I do the same with tieflings.
If you ask a half-orc about his origin, you might hear one of these stories. You might also get a punch in the face for asking such a rude question.
I was half-tempted to end with: That's just how half-orcs roll.

Microsoft VBScript compilation error '800a03e9'
Out of memory
/default.asp, line 0

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.