You know you should employ A-players because they'll produce excellent results for your business, but research shows that's far from the only reason to do everything you can to hire superstars. For one, studies show they act like a magnet for other highly talented folks, creating a virtuous cycle for your hiring efforts. Plus, it's likely they'll encourage their co-workers to up their game as well.

But, of course, wanting to hire A-players and actually managing to do so are two totally different things. Some highly skilled interviewers actually end up being pretty mediocre employees, while a potentially game-changing candidate sometimes make a less impressive first impression. So how do you figure out if the person sitting across from you is really an A-player or just an expert self-promoter?

After hiring nearly 1,000 people for a variety of roles, serial entrepreneur Mitchell Harper thinks he's figured it out. On Medium recently, he ran through his method of sorting true top performers from mere pretenders, including a collection of interview questions he claims can help anyone spot true A-players. Here's a sample:

1. Have you been promoted at least once in your previous role?

The best get promoted, so look for evidence that your potential new hire was regularly given more responsibility. Harper suggests you can even start doing this before the interview: "Look at their LinkedIn profile and see if, at any of their previous companies, they've been promoted. Once is great, twice is amazing, and three times is out of this world."

2. Is this the same role as your last job?

The best employees don't switch companies simply to start doing the exact same thing somewhere else. They move in order to grow and learn. If your interviewee is basically making a straightforward lateral move, that should give you pause, according to Harper.

3. Are you committed to continual learning? Can you prove it?

The best employees aren't the ones with the right skills now. They're the ones who also know how to continually learn and upgrade their abilities. So if you're looking to spot A-players, make sure they not only say they're lifelong learners, but can also prove it with specific examples.

"Ask them what they learned in their previous role. Ask which book they're currently reading. Ask what they plan to learn in the next six to 12 months and how they'll go about doing that," suggests Harper.

4. What do you like about this company? What would you change?

A-players don't want to work just anywhere, so they vet any potential employer extremely well before an interview. For this reason, top talent should be able to talk cogently about your company, its niche, its strengths, and its weakness, and offer a compelling case for why they want to work for you. If your potential hire can't offer any suggestions about what they might like to change or improve at your firm, that's a red flag.

5. What would you like to ask me?

OK, you're probably asking some version of this already when you interview, but Harper believes most hiring managers aren't wringing as much information as they could out of how candidates respond. The questions a prospective team member asks are one of the best ways to separate the mediocre from the truly stellar.

"A-players care about the team they'll be on, their manager, and where you want to take your company moving forward," he insists, and this discernment should be reflected in the quality and quantity of the questions candidates come up with.

What's your best interview questions for spotting A-players?