If we visited the listening rooms of all the people on Audiogon who say that their systems sound like real instruments in real spaces, I'm pretty sure each system would sound different from the others.
Then there is the problem of what does real sound like. The venue you listen in and your seating location while real instruments play greatly affects how that instrument sounds. We all hear differently too, very differently.
Then there is the fact that we are listening to a recording. On the first Stereophile test CD (yellow booklet) there is a track where none other than J Gordon Holt reads an editorial from a very early Sterophile entitled, "Why Hi-Fi Experts Disagree." He is recorded through 19 different microphones and it is not that hard to tell when a microphone change occurs.
So, it seems to me that real instruments in real space is not a hard objective reality. Of course, most of us want our systems to sound as real as possible and I'm striving for that too. I try to get vocals to sound natural. I'm closer than I used to be, but I don't think I'll ever get to the point where a large percentage of my recordings fool me into thinking that there is a real vocalist standing between my speakers singing just for me. YMMV