A tail with a thorn in it / Mixed blessing / There is a hitch / Fly in the ointment

Figuratively: Something good that has a flaw or certain defect (Eliah means the tail of a sheep, which contains much fat).

("Who is a God like you, who pardons iniquity and forgives the transgression of the remnant of His heritage (Micah 7:18) – To whom does He pardon iniquity? To those who forgive transgression. 'The remnant of His heritage' – Rabbi Acha bar Chanina said: 'A tail with a thorn in it' – to the remnant of His heritage, not to all His heritage" – Rosh Hashanah 17a. Also: "For enlightenment is a tail with a thorn in it. If one is worthy, it becomes a potion of life; if not, it becomes a potion of death" – Berdyczewski, Writings II, 87. Also: "For this deed is not a simple deed like other deeds in the world, but a tail with a thorn in it... and the court investigator imposed a ban on the deed" – Sholem Aleichem, Seventy-Five Thousand, 33. Also: "She merited to know several ideas that none of her father's family knew. In any case, I say there was here a tail with a thorn in it" – Agnon, Upon the Handles of the Lock, In Our Youth and in Our Old Age, 218)

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