"Sinlessness" and "taint of sin" do not have to do with Original Sin. Not just in her writings, but in no SDA writings of her time. You can't cite a single person who used these words in the way you're suggesting.
I checked every reference in Ellen White's writings of "taint of sin," or references with the word "taint" and "sin" in the same paragraph, and could not come up with a single reference, not one, where she says that our nature, or flesh, taints us, although there were many dozens of these references.
On the contrary, she writes that we can be free from the taint of sin in this lifetime, which would hardly be possible if having sinful flesh tainted us.
Everyone who by faith obeys God's commandments will reach the condition of sinlessness in which Adam lived before his transgression. (IHP 146)
This is an example of the use of "sinlessness." I've already provided examples of her use of "taint of sin."
As they gaze upon his glory, there flashes before their minds the memory of the Son of Man clad in the garb of humanity. They remember how they treated him, how they refused him, and pressed close to the side of the great apostate. The scenes of Christ's life appear before them in all their clearness. All he did, all he said, the humiliation to which he descended to save them from the taint of sin, rises before them in condemnation.(The Review and Herald, September 5, 1899)
Clearly "taint of sin" does not mean "having a sinful nature" here.
The words of John came forcibly to my mind, "If we say that we have no sin, we deceive ourselves, and the truth is not in us," I was shown that those who triumphantly claim to be sinless, show by their very boasting that they are far from being without taint of sin. (Life Sketches Manuscript, page 121)
Clearly not here either.
Into the heavenly courts will enter no taint of sin. Those who enter there will have obeyed the truth in this world, and will have brought into the life-practice, while on this earth, the principles of heaven. Only such can be allowed to enter heaven, for only those who learn to live in accordance with the principles of heaven will have demonstrated that they would not, after entering heaven, introduce specious devisings that would create a second rebellion. (20 MR 171)
Nor here.
Christ, the second Adam, came in the likeness of sinful flesh. In man's behalf, He became subject to sorrow, to weariness, to hunger, and to thirst. He was subject to temptation, but He yielded not to sin. No taint of sin was upon Him. He declared, "I have kept My Father's commandments [in My earthly life]." (John 15:10.)(8MR 38)
I've been concentrating on references that don't include in Christ, but here's one that does. Note that "taint of sin" is tied to obedience.
Here's another one referencing Christ:
He could endure, because he was without one taint of disloyalty or sin. (YI January 3, 1905)
She uses "taint of sin" similarly to "taint of disloyalty," clearly not having to do with the flesh.
Their dwarfed spirituality is an offense to God. They taint and corrupt the minds of those with whom they associate. (YI June 22, 1899)
Another example of her use of "taint."
He was opposed both at home and abroad, not because he was an evildoer, but because his life was free from every taint of sin, and condemned all impurity.(YI 12/12/95)
Another.
Christ came to receive baptism, not with confession of sins to repentance, for he was without the taint of sin. (YI January 1, 1874)
Another.
Christ, the Redeemer of the world, was not situated where the influences surrounding him were the best calculated to preserve a life of purity and untainted morals, yet he was not contaminated. (YI 2/1/73)
Another.
In His earthly life, Jesus of Nazareth differed from all other men. His entire life was characterized by disinterested benevolence and the beauty of holiness. In His bosom existed the purest love, free from every taint of selfishness and sin. From the beginning of His ministry, men began more clearly to comprehend the character of God.(ST 9/23/08)
Boy there's a lot of these. Many uses of the word "taint," but not a single one suggesting that flesh taints.
Each soul is surrounded by an atmosphere of its own, an atmosphere, it may be, charged with the life-giving power of faith and hope and courage, and sweet with the fragrance of love, or it may be heavy and chill with the gloom of discontent and selfishness, or poisonous with the deadly taint of cherished sin.
One who was innocent of all sin, the One who alone could be the propitiation for sin, because He Himself was obedient. His life was one with God. Not a taint of corruption was upon Him.--Manuscript 42, 1897.
Another one linking "taint" to obedience.
Sin is corrupting in its nature. One man infected with its deadly leprosy may communicate the taint to thousands. (Conflict and Courage, page 120)
Here's one that's particular clear in its point. What is it that taints? It is sin.
Brethren and sisters, we need the reformation that all who are redeemed must have, through the cleansing of mind and heart from every taint of sin.
We may be free from the taint of sin. This would obviously be impossible if our flesh tainted us.
"Learn of me," is the Saviour's command. Yes, learn of Him how to live the Christ life--a life pure and holy, free from any taint of sin.
Another one making the same point.
He who is guided by clean, holy principles will be quick to discern the slightest taint of evil, because he keeps Christ before him as his pattern.
Again, taint has not to do with flesh.
Or it may be heavy and chill with the gloom of discontent and selfishness, or poisonous with the deadly taint of cherished sin.
Cherished sin is that which taints. Note the usage is identical to Jones.
If there is not pollution of mind in yourself, all the surrounding pollution cannot taint or defile you.--Lt 14, 1885.
It is the pollution of mind which taints.
Can I be a Christian, and taint and pollute my soul with sinful, corrupting imaginings?
"Taint" has to do with pollution, which comes about by sin.
The dear children should be taught to flee every taint of sin. In order to do this, they must separate from the hurtful fashions of the world.
We are to flee every taint of sin by being separate from the world.
While sinful amusements are condemned, as they should be, let parents, teachers, and guardians of youth provide in their stead innocent pleasures, which shall not taint or corrupt the morals.
Again we see what taints.
