When it comes to selecting a candidate are there any potential warning signs that signal they might not be a good fit?

I would agree with Greg's comments above. I would also add that not asking your own questions when given the opportunity shows a general disinterest or an implication that you feel you already know everything, which can never be true! Bad-mouthing a former employer is always a no-no. It's fair to say something such as "my personal values aren't aligned with the leadership in that organization", but not ok to get nasty. It never comes across right. Be positive, be eager, do your homework ahead of time and ask thoughtful questions!

If you're the hiring manager/interviewer, are they focused during the interview? Do they check their phone? Were they late to the interview (without a REALLY GOOD reason)? Are they not dressed appropriately for the interview (which could vary based on the industry)? Are there gaps in their resume that aren't explainable? Don't be afraid to ask some of these questions. If you think they have the skills, but still aren't sure, have a couple peers or other team members have a conversation with them too to gauge their reactions to the individual's knowledge, skills, abilities, etc.

For me, a bad interview is when the candidate is smug and rarely gives specific answers or examples when asked a question. Too many times I see candidates that have canned answers and their authenticity is lacking. Also, always be prepared. Dress the part and be confident but also be humble and polite. Employers want to believe they are hiring someone who has a positive attitude and thoughtful but also dedicated and dependable.

Great question! Warning signs - the interviewer only asks 2-4 questions, your interview is 20 minutes and you were scheduled for 30-45 minutes. The interviewer shows signs of disinterest, not looking you in the eye, crossing arms and not taking notes. The interviewee wasn't asked if they had any questions, it is like "thank you for coming, next".

As Molly mentioned don't bad mouth an employer, another manager or employee, use it as a lessons learned scenario such as what you would like to see in your manager, atmosphere of the company and your career.

There was an interview where the interviewee didn't know what position they had applied for, not sure if it was nerves or not, they knew nothing about the company or position. Be prepared!

Another time when the interviewee was not a match to what we were looking for but by the end of the interview, they had changed everyone's mind, they were prepared, eager, willing to learn, had great questions, they wanted to work for our company, they had passion and they were very successful after being hired.