The idea of the perfect sub exists, but much like the perfect man, perfect woman, perfect ten, dragon, and unicorn, its actual existence is a bit suspect and often relegated to the fantasy realm.
So what is the perfect sub? The perfect sub is an ideal. It is the philosophy and state of being you envisioned that would make you the prized possession of the Domme you seek. It is the hopes and dreams a Domme carries into her search for a companion. It is the sub that will perfectly fulfill her desires and keep her existence one of bliss (at least on the home-front).
Since the perfect sub exists only in the mind's eye, what can us subs ever hope to be and what can Dommes ever hope to find? The next best thing, which is the almost perfect sub.
The almost perfect sub fails but learns from his mistakes. He accepts responsibility for his failures and willingly undergoes corrective measures that will reduce them from repeating themselves. He trusts the judgment of his Domme to steer him down a path aimed at perfection.
Perfection is something that should be aspired for. If you aim for the stars and hit the ceiling, you are still above the floor. This is a mindset of subs who wish to perpetually better themselves. They are the almost perfect subs. Dommes should expect this behavior. She should always expect her sub to move closer to the idea of perfection with every action he makes and every attempt should be better and more proficient than the previous one.
The responsibility falls on the shoulders of both parties. The sub must be willing to put forth his all without pride or ego. The almost perfect sub has no pride or ego in his abilities, only pride in being permitted service to his Mistress. He must be mentally prepared to constantly improve himself and work diligently towards that goal.
Dommes have equal responsibility in this task. She must be prepared to shape him into the form she desires most with the patience of a sculptor, slowly watching her creation emerge from the stone. He will fail time and time again and she must be ready to steer him back towards the right path. She must scrutinize every flaw in him and be creative in her ways of purging those flaws. The more time that passes, the closer his image should mirror that of the perfect sub.
Perfect subs aren't born, they're made. Almost perfect subs provide the best raw materials for doing so under the guiding hand of the Domme that is his creator.
However, this is always a work in progress and it is the journey of a lifetime for a Domme and sub to get closer and closer to the stars. If the perfect ten is ever reached, it only proves the existence of eleven.