I'm not sure how to word it but that's very similar to what they accuse Christians of other faiths of doing - cherry picking the things they want to observe instead of believing everything. If all of Ellen's writings are truth, and to insult her is to insult God then even the embarassing stuff must be observed and believed, right?
Yes. She explicitly commanded people not to pick and choose from her writings and said that her work was either all from God or all from Satan:
Many times in my experience I have been called upon to meet the attitude of a certain class who acknowledged that the testimonies were from God, but took the position that this matter and that matter were Sister White's opinion and judgment. This suits those who do not love reproof and correction, and who, if their ideas are crossed, have occasion to explain the difference between the human and the divine. {2MR 87.2}
If the preconceived opinions or particular ideas of some are crossed in being reproved by testimonies, they have a burden at once to make plain their position to discriminate between the testimonies, defining what is Sister White's human judgment and what is the word of the Lord.Everything that sustains their cherished ideas is divine, and the testimonies to correct their errors are human--Sister White's opinions. They make of none effect the counsel of God by their tradition.--Ms 16, 1889, p. 1. ("The Discernment of Truth," circa Jan. 1889. 3SM p. 69.) {2MR 87.3}
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And now, brethren, I entreat you not to interpose between me and the people, and turn away the light which God would have come to them. Do not by your criticisms take out all the force, all the point and power, from the Testimonies. Do not feel that you can dissect them to suit your own ideas, claiming that God has given you ability to discern what is light from heaven and what is the expression of mere human wisdom. If the Testimonies speak not according to the Word of God, reject them.--Testimonies, vol. 5, p. 691. {3SM 46.3}
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In the testimonies sent to Battle Creek, I have given you the light God has given to me. In no case have I given my own judgment or opinion. I have enough to write of what has been shown me, without falling back on my own opinions. You are doing as the children of Israel did again and again. Instead of repenting before God, you reject His words, and attribute all the warnings and reproof to the messenger whom the Lord sends.--Testimony for the Battle Creek Church, pp. 50-58 (1882). {3SM 70.1}
Permit me to express my mind, and yet not my mind, but the word of the Lord.--Letter 89, 1899. (Quoted in Counsels to Writers and Editors, p. 112.) {3SM 70.2}
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Let the Testimonies be judged by their fruits. What is the spirit of their teaching? What has been the result of their influence? "All who desire to do so can acquaint themselves with the fruits of these visions. For seventeen years God has seen fit to let them survive and strengthen against the opposition of Satan's forces and the influence of human agencies that have aided Satan in his work." {5T 671.1}
"God is either teaching His church, reproving their wrongs and strengthening their faith, or He is not. This work is of God, or it is not. God does nothing in partnership with Satan. My work . . . bears the stamp of God or the stamp of the enemy. There is no halfway work in the matter. The Testimonies are of the Spirit of God, or of the devil." [VOL. 4, P. 230.] {5T 671.2}
As the Lord has manifested Himself through the spirit of prophecy, past, present, and future have passed before me. I have been shown faces that I had never seen, and years afterward I knew them when I saw them. I have been aroused from my sleep with a vivid sense of subjects previously presented to my mind; and I have written, at midnight, letters that have gone across the continent and, arriving at a crisis, have saved great disaster to the cause of God. This has been my work for many years. A power has impelled me to reprove and rebuke wrongs that I had not thought of. Is this work of the last thirty-six years from above or from beneath?" [VOL. 5, PP. 64, 65 (1882).] {5T 671.3}
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The statement which you quote from "Testimony," No. 31, that "in these letters which I wrote, in the Testimonies I bear, I am presenting to you that which the Lord has presented to me. I do not write one article in the paper, expressing merely my own ideas. They are what God has opened before me in vision -- the precious rays of light shining from the throne," is correct. It is true concerning the articles in our papers and in the many volumes of my books. I have been instructed in accordance with the Word in the precepts of the law of God. I have been instructed in selecting from the lessons of Christ. Are not the positions taken in my writings in harmony with the teachings of Jesus Christ? If not, point it out to me. {RH, September 6, 1906 par. 1}
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Yet now when I send you a testimony of warning and reproof, many of you declare it to be merely the opinion of Sister White. You have thereby insulted the Spirit of God. You know how the Lord has manifested Himself through the spirit of prophecy. Past, present, and future have passed before me. I have been shown faces that I had never seen, and years afterward I knew them when I saw them. I have been aroused from my sleep with a vivid sense of subjects previously presented to my mind; and I have written, at midnight, letters that have gone across the continent and, arriving at a crisis, have saved great disaster to the cause of God. This has been my work for many years. A power has impelled me to reprove and rebuke wrongs that I had not thought of. Is this work of the last thirty-six years from above or from beneath? {5T 64.3}
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When I went to Colorado I was so burdened for you that, in my weakness, I wrote many pages to be read at your camp meeting. Weak and trembling, I arose at three o'clock in the morning to write to you. God was speaking through clay. You might say that this communication was only a letter. Yes, it was a letter, but prompted by the Spirit of God, to bring before your minds things that had been shown me. In these letters which I write, in the testimonies I bear, I am presenting to you that which the Lord has presented to me. I do not write one article in the paper expressing merely my own ideas. They are what God has opened before me in vision--the precious rays of light shining from the throne. {5T 67.2}
According to EGW herself, there are no other options than either to view her as a prophet and accept everything she wrote as inspired by the Holy Spirit or to reject her as a prophet and consider none of what she wrote inspired by God. She said that none of it was her own opinion and that if people rejected her messages, they were rejecting God. There is no in-between option. Adventists who pick and choose are not in accordance with their own fundamental belief in EGW's writings as "a continuing and authoritative source of truth."