… which means, of course, that bad-personhood should be a dealbreaker. If someone treats other people poorly, eventually that behavior will extend to you, too.
This is different things to different people, so I can only speak in generalities that mean something to me. But is this person a good person? Are they kind to people regardless of whether that person can do something for them? Do they value honesty? Do you feel they are guided by an internal compass that is at least mostly in line with yours?
These qualities aren’t necessarily the sexiest, and they don’t reveal themselves immediately. You can look at someone and tell right away if they’re hot. You can’t look at a person and know what their internal architecture is like. Those are things that will reveal themselves, in ways big and small, and you need to pay attention. Because no one is hot when they’re 90. But some people will still be internally beautiful, and others will still be assholes, and I think everyone knows which type they want by their side long-term.