drag someone or something through the dirt

drag (someone or something) through the dirt

To say or do something that tarnishes someone or something's reputation. It's very unfortunate that a disgruntled former employee has begun dragging our company's good name through the dirt.
See also: dirt, drag, through

drag someone or something through the dirt (or mud)

make damaging allegations about someone or something.
1998 Economist The deputy prime minister…is having his name dragged through the mud.