David is not real -- David is actually a work of art called Slab Man by Duane Hanson that was made 1976 (yes, David is older than I am).
But, boy, does David have a presence.
The first time I saw David at the Cantor Center I didn't actually see David. I was looking around the museum and came upon a gallery that was still under construction. The two outside areas (near the doors) were complete, but the center was still under construction. So, I walked in, noticed one of the workmen (a rather large, husky guy) taking a break, and avoided eye contact while I looked at the art. After all, it was near the end of the day, and this guy's body language was saying he was tired and didn't really want to be bothered. I finished with the gallery and moved on.
It was only a bit later when I went by the same room and saw other people looking at David that I realized he wasn't real. So, yes, I was alone in the same room with David for 10 minutes... while I was looking at each piece of art in turn... and never noticed he wasn't real.
Furthermore, even when photographing David, when you invade his space, you feel it. In fact, I took a few shots right in front of his gaze, and it was quite unsettling.