Rav Hillel Zaks (Mishpacha – "Living the Legend" page 55 June 2, 2014): Rebbetzin Faiga Chaya Zaks was once quoted as having said that 85 percent of the stories told about her father aren't reliable. In response, Rav Hillel and his brother Rav Yaakov Yehoshua asked, "How could di Mamme have said that? It's surely over 90 percent?!"
======== update 6/20/2014
Rav Nosson Kaminetsky (Making of a Godol page xx): (In composing this book, I have generally accepted as authentic stories about earlier generations even when they were not conveyed by my father or some other unusually reliable individual. I was reluctant, of course, to rely on reports that emanated from people whom I considered unable to judge events properly, but I did not suspect anyone of prevaricating intentionally. Similarly, unless the writer was blatantly' tendentious, I assumed that printed facts were credible. (I have this faith in people despite a report by R' Velvel Kercerg that Rebbitzen Feigel Zaks, the Chafetz-Chaim's youngest daughter, told him, "Eighty percent of what they tell about [my father] is not true." I cannot help but assume that in order to bring out bluntly the idea that not everything told about R' Yisrael-Meir Kagan, author of Chafetz Chaim, is true, his daughter exaggerated the percentage of untruths.)
Rav Nosson Kaminetsky(Making of a Godol page xxv): R' Mordkhai Schwab, however, had a negative view of "storytelling" when he told me, "The Satmarer Rav, R' Yoilish Teitelbaum, never told stories because he said, 'You cannot educate through lies - sheker].'" R' Mordkhai agreed with R' Yoilish in reference to stories intended to glorify their principals while dehumanizing them. R' Yoilish echoed a statement by R' Yehoshua'-Yoseph Preil, Rav of the Lithuanian town of Krok. In a 5656 (1896) review of Toldos Yisroel of Zev Ya'avetz, published a year earlier in Warsaw, R' Preil set down the following ethic: "To create stories that never happened and present them as facts for the sake of teaching morals - woe is to the musar precept built on as brittle a foundation as a lie! '' Even hasidim, the celebrated story tellers who are more suspect than others in creating legends about their leaders (from whom the Satmarer Rav was evidently trying to distance himself by his statement), are careful in separating fact from fiction. I was told by R' Shimon Deutchy that he had asked the Lubavitcher Rebbe, R' Menahem-Mendel Schneerson, whether when writing about the arrest and release of his father-in-law, R' Yoseph-Yitzhaq Schneerson, he should mention or omit the fact that R' Yoseph-Yitzhaq's secretary, R' Hayyim Lieberman, was arrested and released with him. (R' Lieberman was opposed to R' Menahem-Mendel's ascendancy to the Lubavitch throne and did not recognize him as Rebbe after he assumed the position.) R' Menahem-Mendel responded, "History must be written [true to its truth]" - and explained his redundancy: "This includes not polishing up any word. Also Pulmus HaMussar (The Musar Controversy), a book about the dispute in the late 5650's (1890's) in which most of the great Torah figures came out publicly against the Musar movement. The author, Musar adherent R' Dov Katz, tells how "many opinions were heard" by him "that we should avoid the entire affair "; but "several Musar personalities" including R' Yehiel-Yankev Weinberg and R' Hatzqel Sarna insisted not only that he should write about the controversy, but - as R' Sarna put it - that "he set down in writing the full affair without omitting any detail, be what it may."

