The totally unacceptable should never become the acceptable. You need to instill a code of ethics, of conduct that is never pierced by systemic or single bad practices. You have to make sure that your culture is such that you are all doing the right things when you know no one is looking.
Yes, we all make mistakes and do bone headed things but I am not talking about being human. I am talking about dishonorable practices that allow others to harm or be harmed.
Make a practice of doing the right thing even when people are not watching and you will be on the right track.