金玉其外，败絮其中
jīn​yù​qí​wài​bài​xù​qí​zhōng

fair without and foul within

金玉其外，败絮其中 金玉其外，敗絮其中 jīn​yù​qí​wài​bài​xù​qí​zhōng
fair without and foul within
(idiom) a gilded exterior but shabby and ruined on the inside; refers to something that looks beautiful or high-quality on the surface but is actually rotten or worthless underneath