Say someone scammed you or someone you know and you know you can scam them back.
If I found out that someone deceived me, I would not deceive him in return. I would simply expose him, preferably in public. So that everyone would know that he is a deceiver.
And if I deceived him in return, I would become a deceiver like him.Ofcourse.
One of the best way to take away things from the scammer without committing thesame crime is to only take back what was stolen from you in a way that nobody(both good & bad judge) will not be able to find fault in.