Well, that is your belief, not mine. When a person chooses to lead a life that is not worthy of respect they show disrespect for the life that was given them. Many are not worthy of respect during their life OR after their death.
Well, as a devout Agnostic (with latent Atheistic tendencies), there's always room for doubt, for the possibility that the whole God, Christ and the Holy Spirit thing is really and truly true. What if it is?
In that light and in that context, I have to believe that
human life is always a good (as opposed to sometimes a good, and sometimes a bad). The dignity of human life, of our life, of your life, flows from creation in the image of God (Gn. 1:26), from redemption by Jesus Christ (Eph. 1:10; 1 Tm 2:4-6), and from our common destiny to share a life with God beyond all corruption (1 Cor. 15:42-57). If you believe any of that, or allow for the possibility, then none of these sources of our dignity takes into account our intellectual or physical capacity, age, life expectancy, or even our deeds and actions. While our abilities to reason, to discern between good and evil, and exercise free will can allow us to know and love our Creator, whoever or whatever that Creator may be, they must be understood in light of our ultimate destiny.
Whether you believe in Creationism, or you are purely an Evolutionist where evolution would select for organisms that give value to their own life (those that cared whether they lived or died lived longer and had more offspring), life is a astounding miracle in any context you wish to apply. If you believe in God, then you know that God created man for incorruption, and made him in the image of His own eternity. So, knowing that, from the first moment of existence, all human beings are therefore eternal beings. Thus, any reasoned vision of a life, whether they be good or evil, living or dead, must reject any "quality of life" or "worthy of respect" calculations of human dignity or respect based on the deeds of our earthly functions.
A new life created is a joyous thing, and the death of a life is a sorrowful thing. Nothing that happens in between those two can change either one. Or at least it shouldn't. Not if you respect life itself. That's not to say that you should respect the person of a Ted Kennedy, or an Osama bin Laden, but the life within, not their actions or deeds, should nevertheless be respected, no matter how or who created it.