TITLE: Can one reuse positive referee reports if paper ends up being rejected?
QUESTION [26 upvotes]: Context: A submission to a very good generalist journal X received one positive referee report recommending publication and two shorter opinions which both deemed the paper a solid and valuable contribution and thus worthy of publication but perhaps not a priority given the backlog this journal has, thus only weakly recommending publication. Given the fairly high standing of the journal this logically resulted in a rejection.
Questions:

Would it be appropriate upon resubmission to a new journal Y to inform the editor of Y of the existing detailed referee report at X? (To be clear: I do not mean sending them the actual report, just making them aware of its existence)

Upshot:the referee's time is not wasted, in particular as the detailed referee report from X is the most thorough report I have ever received (out of over 100), the paper is quite technical in places and the expert referee has spent considerable amount of time on it.
Drawback: The paper starts on the bad footing of being a rejected one, but I think this should not be a big problem if Y is e.g. a specialist journal or if Y is deemed not as "highly ranked" as X. Moreover during the review process at X the referee asked for some clarifications and suggested some improvements which has led to a better paper. I think that even when resubmitting elsewhere we should keep the thank you to an anonymous referee for suggested improvements which already shows the paper was rejected, thus the drawback is there anyway.

If the answer is yes to 1) should one ask the editor of X beforehand whether it is ok to pass on their contact details to potentially transfer the referee report to the editor at Y?

Personally I think the answer is "Yes" to both questions but hearing other people's perspective is very interesting.

REPLY [4 votes]: The following might be useful to have in mind:
if your paper is rejected at journal J1 and submitted at J2, the information at the J2 editorial board that it was rejected at J1 might be considered as negative, especially if the editorial board of J2 considers J1 as being of equal or lower level (which might not coincide with your own appreciation, or of J1's editorial board or referee in case they recommended J2 as alternative — keep in mind that the appreciation of the journal level varies according to subtopics and countries).