A good way of remembering this criterion is the slogan "You can't signal to rubes."

This doesn't seem like it describes your fourth criterion; it reads more like "Rubes can't signal."

I do think that the claim "you can't signal to rubes" is a good one to keep in mind, but like Psychohistorian points out, that limits you to a narrow component of signalling, which I might characterize as spending resources on authority, which is only worthwhile if the audience can recognize authority. If a moviemaker decides to actually use an Bald Eagle cry instead of a Red-tailed Hawk cry, most movie-goers will think (TVTropes link) they got it wrong, and only ornithologists will notice it's correct.