I was thinking about this yesterday -- how art, in general, is ridiculously subjective. A song, a painting, a novel, could be considered either beautiful or ugly according to one thing: the eye of the beholder. Because the beholder is the one who casts judgment on the piece. And because the beholder is the sum total of all his/her past experiences, beliefs, and individual tastes, then that judgment is entirely unique. And valid.
Case in point: I visited a modern museum of art a couple of years ago. And as I was viewing these enormous canvases on the wall (one with a huge line painted beside a large red circle), I marveled at how someone could look at this and call it "art." How someone could spend a hundred thousand dollars on something my five-year-old niece could do with her eyes closed. But the neat thing is, they can. That's their right, their prerogative to look at that painting and admire it. They have just as much right to say they adore that big splotchy circle as I have to say I don't.
When it comes to our writing, when it comes to our scouring the ends of the earth for an agent, and/or publisher, we always need to keep in mind how very subjective this business is. There will be those who read my work and see only a simple line with a red circle -- who will shrug their shoulders at it, or who won't "get" it, might not even like it. And, that's their right. But there might also be (*fingers crossed*) those who read my work and see something else. They'll see beauty there. They'll nod their heads, smile, and consider it "art."
Just like the pair-of-jeans analogy (link here), we writers cannot let ourselves take rejections or critical feedback to heart so much that it paralyzes us or fills us with doubt. Because what we do, what we write, is art. And the very nature of art is subjective.
When we realize that, I think we're better able to release our work into the world (whether it's into friends' hands, or those of agents/publisher), offer it up to them, and accept whatever opinion they hold of it. We don't have to agree with it, but we do need to realize it's theirs, it's valid, and most importantly, it's highly subjective.