Listening To Backbiting (Gheebat)
An unethical act is not allowed at all, no matter if it is against a Muslim or a Non-Muslim. However, if the matter is to save the public interest or a kind of warning against a person whether Muslim or non-Muslim should be revealed to save others from possible harm. This is not backbiting. like reporting a person as a thief, or about an inappropriate marriage proposal, and your counsel is sought then you have to tell if why it is inappropriate.