But it's really hard for emotional and spiritual creatures to be fully objective with the tests. "Science" has changed its mind over and over again about many things. So a certain amount of illusion still exists in the perception of those who think they are being objective. One of my favorite quotes is "You can't believe everything you think." Mystical mentor character "Jones" said that in Andy Andrews' book Return of the Noticer.
Since I've quoted Andy Andrews, I suppose I'd better include a link to his video.
You can see the entire playlist that this video came from by clicking here.
Your "all sane observers" statement seems to assume that all observers are either completely sane or totally psychotic. I'm afraid it's more of a continuum from Spock-like objectivity to emotion to illusion to delusion to phychosis. In art, maybe the real art includes finding just the right sweet spot along that continuum.
Who is really sane? We have to be somewhat mad to achieve the things we do! Especially against all the adds and opposition we come across.