When to Turn Down a Promising Job Candidate The most enjoyable person you ever interviewed is not necessarily the most enjoyable person to employ.

We've all been there.

A candidate submits an application that blows us out of the water. Likewise, during the interview we are impressed -- and yet, they become a liability from day one on the job. This means learning to spot frauds is an essential part of running a successful company. This also means learning when to turn down a promising job candidate.

How do we know when to turn down a promising job candidate?

Why do some of the best candidates sometimes turn out to be the worst employees? Shouldn't our interview processes weed out the people who don't know what they're doing?

Unfortunately, that's not always the case. Just because a person is charming both in real life and on paper does not mean they are right for the job. Founders of startups rely heavily on employees to pull their weight and can't afford to make mistakes in the hiring process.

Related: 8 Science-Backed Techniques That Will Make You More Likeable

Look for these signs to determine when a promising candidate is the wrong fit:

1. Disrespectful attitude.

Few young startups have full HR departments. Many don't even have an HR representative on staff. That's not necessarily the end of the world for small teams. Founders can't afford to invite disrespectful or sexist employees into the fold -- especially with no formal checks to deal with them.

Some questions to ask for to determine whether to turn down this promising candidate.

1. Ask prospective employees about how they feel working in diverse teams.
2. Ask them about their personal prejudices, too. The best candidates will answer that they are aware of how their backgrounds influence their natural biases and work to avoid them.
3. Remember the most charming candidates can still answer even the toughest questions with a smile.

Rather than try to determine the truth of candidates' answers, judge their actions. Interview them alongside current team members of different races, genders, ages and other demographic factors. If the person ignores the woman in the room or talks down to a person of color, that person will inevitably let that attitude affect his or her work at the company.

Related: Tips for Interviewing Every Hiring Manager Should Know

2. Lack of detailed information.

Anyone can talk a big game. Great applicants can even talk about what they would like to do for the company and how they envision their role. However, only the best candidates can back up their experiences with the stories behind them.

Elon Musk loves to ask candidates about their most difficult challenges and the solutions they found. He does this because only people who were truly responsible for a solution (and not just on the team that solved the problem) can answer the question in full.

Ask candidates to talk about their biggest projects, then dive deeper to determine if you should turn down this promising candidate.

1. What other solutions did they consider before they settled on the right one?
2. Who did they consult along the way?
3. What would they do differently next time? If they really accomplished what their applications claim, they will be able to answer follow-up questions with detailed responses.

3. Bad vibes

Sometimes, an applicant provides all the right answers, dresses the right way and appears to fit the culture, but there's still something off but promising job candidates learn how to answer the questions correctly. Don't let gut instinct prevent you from hiring the right person but don't ignore your intuition if you can't shake that bad feeling.

In his book Blink, Malcolm Gladwell discusses how we form impressions about people within a few seconds of meeting them. Turns out, we're usually right -- but not always. Gladwell also points out that stereotypes, including negative ones about race and gender, are just as powerful as our correct assessments of other factors.

"Bad feelings" might not be the most reliable when hiring someone who should be disqualified, but even in today's data-driven business world, human instinct remains useful. When you first see a candidate, take note of the kind of impression that person gives you. Does she appear competent and kind, or rash and unmotivated?

File away your "first impression" information at first, because your instincts could easily be wrong.

You don't want to make all your hiring decisions based on unreliable feelings. Only go back to that feeling at the end of the process when you're deciding between a few top candidates. If you find yourself looking for a reason not to hire someone, there's probably a good subconscious reason for it. Just consider whether you're acting from a place of personal bias before you make the call. Effective business operations are key to running a long term business.

Related: The Science of the First Impression: 5 Elements of a Great First Impression

A promising candidate is hard to turn down.

Hiring at a startup is hard enough without turning away great candidates. However, firing someone you never should have hired is much harder than turning that person down after the second interview. Use these tie-breaking factors to help figure out which candidates are the real deal and which ones you would be better off without.