[Note: I obviously am no longer actively blogging but noticed that this has been sitting in draft form for over five years (originally scheduled for 11/26/13) and is essentially complete so I wish to go ahead and publish it. I believe I intended on elaborating on the Gemara's admonition not to pasken based upon a ma'aseh rav unless one is told expressly that it is the halachah (at which point it is considered among the most authoritative pesak halachah, as I recall). It appears, however, that the relevant citation is in the Divrei Yatziv and while more elaboration might be in order, the post is sufficient without it--Yirmiahu]
Perversely, the criticism of the Terumat HaDeshen was turned on its head and applied to the Leket Yosher. Specifically, the Sanzer Rebbi in his Divrei Yatziv (E.A. 39), claims that one cannot rely upon the Leket Yosher as it records actual events and one cannot decide halakha from events. This is inapposite of those who complain that the Terumat HaDeshen is not reliable because the questions do not relate to real events. (http://seforim.blogspot.com/2008/01/in-recent-discussion-in-journal-or.html)
The choice of the adjective “perversely” is of dubious propriety even if the criticism was correct, it is however particularly unfortunate since the observation does not accurately reflect the position of the Divrei Yatziv. The criticism of using Terumat haDeshen, as it was presented, is about the propriety of using a work that answers hypothetical questions to decide practical halachah.
To actually turn this objection “on its head” would be to argue that practical halachah should not be based on works that answer real life questions, i.e. traditional Sheilos v’Teshuvos. This was not, clearly, the objection of the Divrei Yatziv (itself a Sheilos v’Teshuvos work). Instead the concern of the Divrei Yatziv was that the particular answer to the question was based off of an observation of how a Rav behaved, i.e. a maaseh rav. The Sanz-Klausenberger Rebbe did not object to utilizing the answer to a practical question as precedent but an inappropriate inference from observation rather than p'sak:
מהלקט יושר. הנה לאו מר בר רב אשי חתים עלה, ומעכת"ה בעצמו כתב שאין לסמוך עליו, והוא בבחינת אין לומדין הלכה מפי מעשה [ב"ב ק"ל ע"ב]
With the understanding that the objection to the opinion of the Leket Yosher was particular to the methodology of the given halachic opinion rather than on the nature of the work itself makes it clear why, "the Sanzer Rebbi himself is at least five other places in Divrei Yatziv cites with approval the Leket Yosher" (ibid).