"All things whatsoever God in his infinite wisdom has seen fit and proper to reveal to us, while we are dwelling in mortality, in regard to our mortal bodies, are revealed to us in the abstract, and independent of affinity of this mortal tabernacle, but are revealed to our spirits precisely as though we had no bodies at all."
TPJS p. 355
When Joseph had some of his revelations it's interesting to ask what an onlooker who was at the same place may have seen. Someone looking through the window for example may have just seen a guy sitting there, or lying there, or looking at a piece of glass or a stone. We may miss the point of how God works if we think about setting up a hidden video camera while President Monson is in the temple in order to get a sneak peak at some special secret meeting.
While Joseph Smith may have been gazing into heaven, the guy 5 feet away may have seen Joseph gazing upwards, but when he looked at the wall or ceiling would have wondered what is so special about those rafters. It's possible no one else in the room may have any idea what was occurring. You can't cheat that, or trick your way in with technology, or engineering. Had we been able to peak out around some trees in the sacred grove, we may have seen a Joseph passed out on the ground, meanwhile he was in contact with God.
There are other times when the Savior has been visible to the parties present but was not recognized. As on the road to Emmaus. The two disciples spoke with the risen Lord for some length of time without recognizing who they were speaking with. The indication was the burning in their hearts as He spoke.
Then there are times when people knew who he was, and could see him, but still couldn't "see" him for who he truly was.
We can't rely on another's faith. At some point we must allow the Lord to assist us in developing our own faith, degree by degree. Who can doubt that we need eyes of faith? Without it, it will be hard to see with our eyes themselves. Faith is a gift, and it's the first principle of the Gospel.