unscrupulous
adj.adj. having no moral principles and not caring about being fair or honest. You use this to describe someone who will do anything to get what they want, even if it hurts others.
adj. showing a lack of moral principles or ethical standards. Often describes individuals or businesses that exploit others for personal gain or profit.
The unscrupulous salesman lied about the car's history.
Unscrupulous landlords sometimes refuse to return security deposits even when the apartment is left in perfect condition.
The investigation revealed how unscrupulous financial advisors had systematically targeted elderly clients, convincing them to move their life savings into high-risk, high-commission investment vehicles.
From un- + scrupulous.
Typically used attributively before a noun like 'person', 'business', or 'method'.