It's not him. It's the chip. He punched Tara in the face to see if she had any demon in her and she didn't and it hurt him. The only 'human' he's been able to hurt with the chip in is Buffy, and that's after she came back from the dead. I don't even think he could hurt Dawn, and she was a celestial key (not that he tried). So half humans or demon hybrids or zombies or vampire (who used to be humans and now aren't) are all fair game. Just no human-humans. And that includes witches. From his world, at least, since they're not a species as much as a class.


(add: and he does paint his own nails. black. punk hardcore for liiiiiiiiiiife)