1. They badmouth their ex. If that's how they talk about them, it's probably how they'll talk about you sooner or later.
2. They only talk about themselves. They might just be nervous. But if it's an ongoing thing, they're probably not worth it. And they almost definitely have a big ego.
3. They're rude to the waiter. Best case scenario, they're just nervous and want to impress you by making sure everything goes well. But chances are they're just a jerk.
4. They drink too much. A couple drinks can loosen you up. And it's not uncommon to drink a little too much when you're nervous. But it's never a good sign if they get fall-down DRUNK on your first date.
5. They admit they've "ghosted" on people before. That's where you just stop talking to someone instead of breaking things off. If they've done it before, there's a decent chance they'll do it again. So just save yourself the heartache.
6. They seem bored. They might just be trying to play it cool. But if you get the impression they're bored by YOU, don't waste any more time on them.