Hiring a new employee can be challenging, but the end result is worth it -- if you find the right candidate. Unfortunately, while lots of really great workers are looking for jobs, there are also some nightmare employees who'll be nothing but trouble from day one.

And when you bring a bad worker on board, you waste time and money -- and might even put your company at risk. 

While it can sometimes be hard to tell if a job seeker is the best person for an open position, certain red flags suggest that a candidate is absolutely the wrong person. If a potential employee is guilty of any of the following, it's time to end the process politely and move on to another candidate. 

Young woman at a job interview with two professionals.

Image source: Getty Images.

1. Showing up late for an interview

You don't want to deal with an employee who's constantly late. More to the point, showing up late for something as important as an interview shows a candidate either doesn't care or has poor time-management skills. Unless there was a major unexpected traffic disaster, beware of the candidate who shows up late.

 2. Submitting application materials with major mistakes

You want the work your employees produce to be error-free. If they can't get their resume or application right, it's unlikely they'll produce flawless work once they're collecting a paycheck. Application materials should not only be well written and free of typos and grammatical mistakes, but ideally they'll also be tailored to the job. This shows a candidate is really excited about working for you. 

3. Coming unprepared to ask questions

Candidates who have a strong interest in your company will have done research about it and will come prepared with questions. They'll be curious to learn as much as possible about the work. Even if job seekers otherwise ace the interview, it's a big problem when they don't have questions aimed at making sure the job is a good fit, with a company culture that works for them. 

4. Behaving rudely to support staff

Good employees work well on a team and treat everyone with respect. If interviewees are polite to you but brusque with the receptionist or don't take the time to thank the security guard who opened the door to the office, they may not have the people skills or emotional IQ necessary to do well at your workplace. 

5. Bad-mouthing a past employer

While there's always a chance a candidate's last job was truly terrible, good candidates have enough tact not to mention problems when talking to a potential new employer. Interviewees who are full of complaints are likely to be difficult and demanding. Hiring them is a bad idea unless you want your company to be the subject of their derision in a few months. 

6. Lacking an answer about why they want the job

Most talented people have a career plan and aren't just looking for any open position. When interviewees have no answer about why they want to work for you, either they aren't ambitious or they're just looking to collect a paycheck while waiting for a job they really want. 

7. Offering no explanation for job-hopping or employment gaps

A history of changing employers or a gap in employment history won't necessarily disqualify a candidate who has a good reason for a spotty job history. But if someone has had 10 employers in the past two years or hasn't worked for a decade and can't say why, your company probably shouldn't hire that candidate. 

Don't ignore red flags when there are great candidates out there

While it may seem nitpicky to disregard a candidate for being a little late or for typos in a resume, remember that most people put their best foot forward during the interview process. Attitude, punctuality, and attention to detail rarely improve after being hired, so move on from a candidate who doesn't care enough and find someone to hire who's excited about working for your organization.