“美中不足”，字面意思是“beautiful yet incomplete”，指总的方面虽然很好，但局部不够完善，有缺陷（a flaw in an apparently perfect thing）。与英文俗语“fly in the ointment”意思相近，表示“a flaw or imperfection that detracts from something positive；a drawback or detrimental factor”。

例句：

你的新工作听起来实在太好了——工作有趣味，待遇高，时间短。有什么美中不足的地方吗?

Your new job sounds too good to be true -- interesting work, high pay, short hours. Isn't there any fly in the ointment?

这个原本完美的婚礼上唯一美中不足的就是新娘走在过道上时绊倒了。

The only fly in the ointment in an otherwise perfect wedding day was the fact that the bride tripped when walking down the aisle.