How they talk about their family:
Here’s where you can find out a lot: if they’re a born victim, an immature baby or spoiled brat, or if they have an understanding of their own nature or any sense of humanity. Highly subjective.
How they talk about their friends:
Someone who surrounds themselves with people that they call “dumbasses” or “name-drops” e.g. “my friend is a concert promoter, rocket scientist, etc.” If they spend more time talking about their friends–especially to make fun of them, not good.
How they talk about ex-friends/partners/lovers:
“What a crazy bitch!” is an excellent example of a warning shot off the port bow that this is not a nice person.
How they talk about themselves:
Self-haters, insecurities, arrogance, etc…
And definitely the clue about how they treat other people they come in casual contact with–and how considerate and thoughtful they are when they drive, stuff like that. Sorry I don’t have a top ten, but this is all I can think of off the top of my head. These things are all really subjective anyway, you might really like a nattering nabob of negativism for a lover and this could be part of your “what I want” list if you’re into that sort of thing. Sometimes people find inconsistancy and cruelty titillating. So you never know, I mean, these mean people must breed somehow.