What are good Qs to check the emotional state of a person before hiring?

Emotional state sounds like the way someone feels in a given moment - like whether I'm in a good mood today or I'm having a bad day. Maybe you're talking about mental health? Or personality testing? They're different things (and each of them has questionable usefulness to hiring).

Did they make it to the interview? Are they passionate about what they do and okay spending their life earning your company money and being paid as less as possible? Sounds like a healthy person to me! They're hired. In all seriousness, it may be too big of a task to try to learn everything about the person before you get a chance to work with them. If they're not a right fit, it will show in time. It sounds like you've been burned before with employees who were going through some stuff or might have not been of sound mind. What's your motivation behind asking?

You're getting roasted enough, so I'll assume you might have meant their behavior i.e. ego, tact, trustingness, etc.

* Tell me about a time when you disagreed with a coworker/manager.

* Tell me about a time you had to persuade someone to see your point of view.

* Tell me about a time you caused a major production issue.

These are pretty standard behavioral questions. The key is to focus on a specific example, not a hypothetical. Look for their impact and their actions.

What do you want to accomplish, not hiring depressed people? That seems somewhat illegal.

Maybe you should be checking your emotional state and ask yourself if you're really the person who should be hiring based on your perception of an interviewee's mental health.