a black mark against someone
a black mark against (one)
A mistake or the negative impact thereof that permanently harms one's reputation. Jerry's unpaid speeding ticket has been a black mark against him that prevented him from getting a job as a delivery man. They let me keep my job after I got caught, but the transgression became a black mark against me for the rest of my career. That team's general manager has had a black mark against him ever since he traded their ace pitcher for next-to-nothing.
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.
a black mark against someonesomething that someone has done that is disliked or disapproved of by other people.
The literal meaning of the phrase is a black cross or spot marked against the name of a person who has done something wrong.
Farlex Partner Idioms Dictionary © Farlex 2017