A nasty piece of work
Definition 1 of 1
Pro Tip 1/3Negative Connotation
Indicates strong disapproval toward someone's behavior or personality, often due to unethical actions or attitude. 
After learning he bullied his classmates, I realized he's a nasty piece of work.
Pro Tip 2/3Colloquial Use
Commonly used in informal spoken language, not suitable for formal writing unless quoting speech. 
At the reunion, everyone agreed that our old boss was a nasty piece of work.
Pro Tip 3/3Emotional Weight
Carries an emotional punch, can hurt feelings if used carelessly about someone. 
She didn't hold back and told him he was a nasty piece of work to his face.