under what conditions should you do so?

NO! It is never an ideal practice as it sure would always backfire. There is a Yoruba adage that says "Bi a ba ta ara ile eni lopo, bo ba di owon, a o le rira" meaning, when you say bad things about your relatives, you only make them lose respect before people and that is the way people will treat them as well.

yes, its very counterproductive.

but its possible people are not aware of the implications.

when esau sold his birthright for pottage, he never got it back.

Do not wash ur dirty linens outside