Premanand Maharaj Ji
What is adharma, and how do I know what is wrong?
Adharma is what scripture forbids
What scripture tells us to do is dharma, and what it forbids is adharma. Read scripture and keep the company of saints so you know your duty, and listen to the quiet inner voice that says 'this is wrong'.
Otherwise, wherever we want to do adharma, a voice from within will come. You will see, from inside comes 'this is wrong', but it is a very faint voice.