Also possible! But normally I'd be able to tell, even if they looked human. Paradoxically, only an extremely powerful ayakashi would be able to hide its own spiritual energy that effectively, and it's pretty unusual for them to try.

["Pretty unusual" because he has seen it, particularly with spirits who yearned to be human so strongly that they deluded even themselves about their status. But even then, there were tells.]

It does, doesn't it? No offense to you and your profession, but we exorcists should probably feel embarrassed about that. [Childish. But then again, who is he to be throwing stones? He's got his own biases and stubbornness.] It's an interesting bit of human nature, isn't it? Too bad we had to go to hell to figure it out.