Sometimes it's crystal clear that someone you brought in for a job interview just isn't the right fit for the role. Maybe he doesn't have the skills, for example, or perhaps she's a certified grade-A jerk. But other times the signs that a potential new hire won't pan out for your company can be more subtle.

What are these smaller signs that a candidate isn't quite right? A recent Quora thread responding to someone who asked "What are some of the biggest red flags in an interviewee?" provided a wealth of great responses from some top-notch recruiters and entrepreneurs who together have hired thousands and thousands of people.

If you see these red flags, they suggest, seriously consider giving that candidate a pass, even if the person seems otherwise qualified.

1. Victim mentality.

This is the biggest red flag of them all for Sarah Smith, a VP in HR at Quora. "When I ask, 'Tell me about your interest in this role,' and I get an answer along the lines of 'Well, I'm at Facebook/Google/Microsoft and have really tapped out on what I can learn here. There's no more room for me to grow,' you've pretty much lost me," she says. "I've worked in some very mundane jobs earlier in my career and have never been 'bored.' There is always something to learn."

Likewise, Smith gets concerned when potential new hires talk about a previous boss "hating" them or the company "limiting" them. In short, if you're not learning, it's your fault. Blaming others is a sure sign of lack of initiative.

2. Job-hopping.

There's some disagreement about what exactly counts as job-hopping these days, but several recruiters mentioned that short terms of employment are still a big turnoff. "I don't immediately reject applicants who have a shorter term at one company, but I'd certainly want to know why," writes Smith, for example. "I'd want to understand ... whether the position we're considering them for is likely a much better fit."

"A good contractor is hard to find. Companies will do anything in their power to keep them. I know, I work with dozens of them, with disparate corporate cultures. If you have one or two short-term assignments, that's normal. But if most or all of them are less than six months, sirens start going off," agrees corporate recruiter Dan Holliday.

3. Obsessing about compensation.

Of course, everyone is interested in pay, but a candidate who focuses too much on compensation up front worries Adam Seabrook, co-founder of Betterteam (and previously a recruiter for Bigcommerce, Atlassian, and other companies). "Generally I will raise this once at the beginning of the interview, and if you are within the range for the role we can move on and talk about other things," he explains. "Once salary has been discussed, try not to keep going back to this," he advises job seekers, "as a candidate who is primarily motivated by money rarely gets past the first interview."

4. Video interviews with weird backgrounds.

"I won't list some of the horrendous things I have seen in the background of candidate video interviews. You really don't want a boardroom of people seeing half the stuff you have laying about your house. Be sure to check behind you and make sure there is nothing there you do not want the interviewer to see. Also make sure you have privacy so nobody wanders into view. If you want to dramatically improve your video interview quality, follow this video on how to set up your lighting," Seabrook tells those interviewing at a distance.

5. Too polished.

Wait, isn't it a good thing when the candidate has all the answers? Not necessarily, warns Holliday. "I have a collection of questions that few people can be prepared for. If you are, then that's not a knockout blow, but it does worry me," he writes. "When I ask, 'Tell me about your worst failure on a job, where you thought you were gonna get fired. Explain the outcome' and you have some smarmy, slick answer, I start to worry. Likewise, if you say, 'Oh, I've never done that.' Then (a) you aren't bold enough, bold people take risks and sometimes those risks backfire, and (b) you're probably lying anyway."

6. No questions (or canned questions).

"A good interview is a conversation, where both sides are engaged. The purpose is to discover if the position is a match. If the candidate asks no questions, it's a red flag," cautions Mira Zaslove, a product manager at Cisco.

The only thing worse than blanking out entirely when you're asked if you have any questions is asking canned questions, according to Benjamin Holder, manager of college recruiting at GradStaff. "I interview candidates every day that seem to be asking questions just for the sake of asking questions. It's almost as if they think they made it through the interview, and the only remaining task is to check a few questions off of a prepared list. Don't do this. Interviewers can see right through it," he writes. The best candidates ask only questions they actually want the answer to.

7. Bragging about other offers.

Don't be impressed by candidates who seem to be in hot demand, Zaslove also notes. They're probably not really that interested in the job. "When candidates blatantly brag about other offers, it signals that they aren't committed to this particular job. It's a red flag that indicates they will probably accept another offer, using my offer as leverage. And if they do join, as a hiring manager, I worry that they will always be thinking 'what if.' I've seen these candidates quit when the going gets tough, to take another 'greener pasture' position," she writes.

8. Not knowing what they don't know.

Confidence is great, but too much bravado can get in the way of actual learning (especially for technical roles), warns John L. Miller, who has interviewed candidates for Microsoft, Amazon, Google, and Oracle. "It's OK to guess if you admit you're guessing, but guessing and saying you're positive you're right? How can I trust you to build ANYTHING if you don't know what you need to learn or need help on?" he says.

9. An extreme commute.

You're looking for someone who is going to stick around at your company. If they have to drive hours to get there, Zaslove wonders, is that really likely?  She worries "if the candidate complains about the commute, parking, or traffic. I've had a few good people quit after only a few weeks on the job because the commute was just too much. Some people can handle the extra time or will move for the right opportunity, but many will be repeatedly late for work, or just quit."

10. Poor listening skills.

Founder Ramkumar Balaraman memorably calls this the "Sarah Palin" problem. "Poor language skills aren't a deal breaker, depending on the role. Nor is being introverted or reserved," he writes, "but poor listening skills, i.e., repeatedly misunderstanding questions (whether intentional or not), are a red flag."

What other red flags would you add to this list?