Curate's egg
IDIOM DERIVED FROM TWO NEAR-IDENTICAL 19TH CENTURY CARTOONS
A Curate's egg; Curates egg; Curate's Egg; Vicar's egg
A "curate's egg" is something described as partly bad and partly good. In its original usage, it referred to something that is obviously and entirely bad, but is described out of politeness as nonetheless having good features that redeem it.