Value implies that the thing has worth. With this in mind, how do you then reconcile the concept of "are without rights or worth", If, by the very definition, any object that you own, purchase, or create, has value be it perceived or real?

It may have some worth to you - the owner - but not as a person have worth. Meaning, when it stops having worth - being old, sick or just getting boring - you rid yourself of it without any thoughts on how the 'thing' feels about it.

Where does the line exist in the objectification that separates reality from fantasy.

In that when it comes to it, you do not really see the person as a thing.

You obviously chose your submissive based on a set of values or criteria that made her or him attractive to you in some fashion. Some portion of this was the personality portion of that persons makeup. If part of your objectification, or deconstruction, the the modification of this personality portion, at what point do you change the very thing that made this person attractive to you.

It is not uncommon also in vanilla relationships to fall in love with some traits in the other person, only to set about to change them. I think it possible for some Dom(mes) to find conquering a person interesting, then, when they are, they loose interest.

Submissives. At what point do such fundamental changes go over the line into hard limit areas? How do you judge?

When the Dom(me) truly does not take the interests of the sub into account, but is only focused on his or her own gratification.