Perfection can sometimes be the objective of a portrait. Managing to portray the person without losing anything from the being to the representation. Yet, perfection is boring. Nothing is perfect, nothing can be. There is always a flaw. But flaws provoke enjoyment.
Perfection is a set point. While things can be seen as good and better, perfect, by definition, would be above the rest. It would mean the loss of comparison, the loss of personal preference. Perfection would have to be universally acknowledged.
Perfection is also dangerous. Something perfect becomes infinite. A perfect painting could have anyone lose themselves at sight. The very fact that it is perfect would ruin everything else, including reality. The ability of anyone to reach such an absolute would render any other attempts irrelevant.
The everyday use of the word refers to perfection in technique, in craftsmanship. This breed of perfection is rather abject. It is fake. The simple idea of something flawless scares, though in the case of pure technique it is empty; thus bearable.
Emotion in a work of art affects the technique and therefore makes reaching perfection impossible. Again it is this vulnerability due to the flaws and mind of the artist that make the production interesting.
Imagine a world of perfect human beings, a monotonous species with a stale existence. Imperfection is the essence and beauty of our condition.