آدم بد دهن چی میشه؟

Question

کسی که به طور روتین حرفهای زشت و زننده استفاده میکنه و بی ادبی براش عادی است

Answer 1

foul-mouthed

Answer 2

In addition to my friend's answer, I can add these:

foul language

dirty

abusive

colorful language

...

These can be used for describing both a specific person and his words.