curate's egg
noun
- Brit. a thing that is partly good and partly bad〈英〉好坏参半的东西:
this book is a bit of a curate's egg.
这本书有点良莠参半。
词源
early 20th cent.: from a cartoon in Punch (1895) depicting a meek curate who, given a stale egg at the bishop's table, assures his host that 'parts of it are excellent'.