Dirtiest

To make (something) dirty.

To stain or tarnish (somebody) with dishonor.

To debase by distorting the real nature of (something).

To become soiled.

Unclean; covered with or containing unpleasant substances such as dirt or grime.

"Despite a walk in the rain, my shoes weren't too dirty."

That makes one unclean; corrupting, infecting.

"Don't put that in your mouth, dear. It's dirty."

Morally unclean; obscene or indecent, especially sexually.

"At the reception, Uncle Nick got drunk and told dirty jokes to the bridesmaids."

Dishonourable; violating accepted standards or rules.

"He might have scored, but it was a dirty trick that won him the penalty."