1.
vice; immorality; unscrupulous conduct
Morally corrupt character or dishonest, unethical behavior. Frequently used attributively to label dishonest businesses and operators, as in 悪徳業者.
悪徳商法にだまされた。
I was deceived by a fraudulent sales scheme.
Most often appears as a prefix-like modifier labeling dishonest businesses and their methods.