curate's egg

Từ điển Oxford Advanced Learner 8th

curate’s egg [curates egg] BrE NAmE noun [sing]
a thing that is partly good and partly bad. The phrase comes from a ↑cartoon in the British magazine ↑Punch in 1895, in which a nervous young ↑curate (= priest) is having breakfast with a ↑bishop. The bishop says ‘I’m afraid you’ve got a bad egg there’ and the curate, not wanting to upset the bishop, replies, ‘Oh no, my Lord! … Parts of it are excellent!’
•Their investment plan shows the familiar curate’s egg pattern of some bits doing well and others doing badly.