lackluster

乏味的（形容词）

(adjective) Lacking vitality or brilliance, usually because of a lack of effort. (NOTE: British spelling: lacklustre).

EXAMPLE: The audience was disappointed and rather angry when the famous musician performed in a lackluster manner after arriving late for the concert.

音乐会上，这位著名音乐家演出迟到，表演平淡乏味，观众深感失望和气愤。

the kiss of death

致命一击（传统表达法）

Traditional expression describing something that is the final action before something collapses or otherwise ends; a fatal act.

EXAMPLE: The embezzling scandal involving our chief accountant was the kiss of death for our financially troubled company, and it closed within a few months.

对我们这家财务陷入麻烦的公司来说，这起牵涉到我们的首席会计师的贪污丑闻是致命一击，没过几个月，公司就倒闭了。