I think the only time it can help is if someone is being truly harassed by something regarding the other person and they are looking for an empowering Godly solution to work through it so they can move on to a more open spiritual solution.
So for instance if a person at the office place is being abusive and others share they have experienced the same thing. Thus allowing the group to know they are not alone. Then the group may discuss individuals positive solutions to move on and get about a productive, Godly way of life and not live in the resentment which is like acid. Just my two cents. I always ask myself, "where is this conversation going? Is it just to harass another or is it leading to one of the two talking being more at peace and empowered in a Godly way?" If it is the former, I generally steer the conversation away to another subject that is the latter.
But I’m assuming it’s OK to say nice things about someone behind their back? I like to do that, but will cease if that counts as gossiping or involving myself in someone else’s life.