I've found that listening to other people vent about people that I don't know well poisons any relationship I'm going to later have with them. There are people who are otherwise very good people that I can't manage to stop disliking and it all started with my friend Jane Doe who mentioned to me that she was fed up with Mary Smith always bumming rides off her. Early impressions of a person are a big deal, and I imagine I would currently have a much better relationship with Mary Smith if I could stop thinking of her as the bummer of rides who used to make Jane Doe leave parties earlier than she wanted to so that she could go home when she wanted. Petty, and ridiculous, but no matter how much I work on it, I just can't overcome it.

What's really best for relationships is discussing the problem with the person who is causing it. Or failing that, with people who will never ever meet that person. So it becomes "asking for advice/venting about my relative who doesn't use dreamwidth or LJ or whatever" to people who live so far away from the relative that it doesn't matter.