警界的腐败不止是几个害群之马而已。

Police corruption is not just a few rotten apples.

约翰是匹害群之马，被开除了党籍。

John was a black sheep and was driven out of the Party.

我在厂里好比是一家之主，我不能容忍那种害群之马。

As the owner of the factory I'm like the head of a family, and as such I can't allow any black sheep among my employees.

麦克是公司的黑羊。[正译]麦克是公司的害群之马。

Mike is the black sheep of the company.

败类：一家之中或其他集体中令人不满或名誉不好的成员；害群之马，败家子。

Black sheep: a member of a family or other group who is considered undesirable or disreputable.