feet of clay 泥足；缺点；缺陷；（受人崇仰的人的）不为人知的严重缺点(或缺陷)

【例句】
When those idols are found to have feet of clay, the pain of disenchantment can be profound.
当人们发现那些偶像有严重的缺陷时，会产生无比痛苦的失落感。

I discovered that my favourite uncle had feet of clay, he had stolen money from my father.
我发现我最喜欢的叔叔也有不为人所知的缺点，他竟偷我父亲的钱。