Let's start with my original post.
If I'm very familiar with a classical piece that won't give me technical difficulties I can probably perform it at first sight.
Just to be clear:
1) "classical piece" means classical period as in Haydn/Mozart/etc.
2) "very familiar" means that I've at the very least followed the score while listening to the work many, many times (sometimes I obsess with a work and listen to a work played by every performer I can find, although this hasn't happened to a classical period piece for many years).
Sorry if this annoys you
Why would I be annoyed? Like you, I come on these forums to have a discussion
.
but I can't imagine someone performing while just reading the notes.
Well, I'm going to blow your mind!
I've seen my former teacher sight read Bach WTC fugues that he never played. Sure, he used more pedal than I would have liked and had odd phrasing and voicing here and there, but his playing was still enjoyable. I'm 100% positive he may have examined the scores and had prior exposure to the works, but he claimed to never have played a key of the works until that day.
Another day, for fun I printed out a bunch of random works. Surprisingly he claimed to have already studied and practiced all but one of the pieces I printed out - Prok's Op. 11. He said he heard the piece in high school and was interested in looking at it. He started reading; until the 4th page, minus a few breaks in tempo when his hands crossed over for relatively big leaps, I promise you that you would have thought he thoroughly studied the work. For the record, I was extremely familiar with the work and he didn't fake anything until the 4th page where he started leaving out notes.
My former teacher probably is an exception especially since he's Juilliard trained and claimed to be an exceptional sight reader even amongst his classmates.
For me what's more surprising is that he claimed his teacher at Juilliard can pretty much perform anything in the standard repertoire at first sight if there's time to skim and analyze. I would assume a Juilliard faculty member's repertoire is probably immense, so there's not much that's in the standard repertoire he hasn't played before.
I know you can play it and all
The number of different conceptions on what it means to "play" something exceeds the number of people in the world.
For me, when I say someone can "play" a piece, I mean that someone can give a performance that is or seems to be musically thought out regardless of whether or the performance conforms to accepted norms.
Going back to my former post, my definition of being very familiar implies that I have fully formed musical ideas of the works. All I have to do is execute. I already know how the work sounds, I know what I want to do, I stated there are no technical difficulties so therefore I can do everything required of me to perform the work, and I have the notes in front of me. How could anyone not give a convincing performance in situations like this?
but it takes a lot of time to turn a chart into a piece of art. 
A bit pretentious aren't we?
According to you, a vital factor for producing a piece of art is time. I'm sorry, but I strongly disagree with you...
What is objectively a piece of art?
According to Britannica Online, art is the "use of skill and imagination in the creation of aesthetic objects, environments, or experiences that can be shared with others." Therefore, my performance no matter how repulsive it is to you, is still art.
My god I was really bored!
Topic: Sight Reading