A "curate's egg" describes something that is mostly or partly bad, but partly good.
In its original context, the term refers to something that is obviously and essentially bad, but is euphemistically described as nonetheless having good features credited with undue redeeming power.
Its modern usage varies. Some authorities define it as something that is an indeterminate mix of good and bad and others say it implies a preponderance of bad qualities.
The term derives from a cartoon published in the humorous British magazine Punch on 9 November 1895. Drawn by George du Maurier and titled True Humility, it pictures a timid-looking curate eating breakfast in his bishop's house. The bishop says: "I'm afraid you've got a bad egg, Mr Jones." The curate replies, desperate not to offend his eminent host and ultimate employer: "Oh no, my Lord, I assure you that parts of it are excellent!" (This clearly cannot be true of a bad egg.)
The final issue of Punch, published in 1992, reprinted the cartoon with the caption: Curate: This f***ing egg's off! Thus Punch drew a contrast with the modern era, implying that younger people have little concern for the niceties of Victorian good manners towards those once considered their social superiors.
The following are some examples of actual usage of the term "curate's egg":