You loved the resumé. You respect the referral. Skills, qualifications, experience--everything looks great.

Then the candidate blows the interview, sometimes within seconds.

Sure, interviewers make stupid mistakes. Sure, interviewers make snap decisions--often incorrect ones. But I was curious what basic mistakes job candidates often make during interviews, so I asked John Ricco of The Atlantic Group, an executive search firm specializing in financial services and investor relations, for the most common ways his clients have blown their interviews.

See if any of your job candidates have made these basic mistakes:

They don't know their own resumés.

Many candidates, especially those with limited experience, are tempted to list 10 or 12 skills and then can't speak intelligently about their abilities, much less describe any projects or accomplishments related to those skills.

That's especially common when a particular skill is hot in a particular industry. For example, expertise with certain kinds of analytics certain databases or analytics is a key quality hedge funds look for.

But just because you list it doesn't mean you can do it. More candidates get bounced for this reason than any other. Every interviewer knows that resumés are designed to put the candidate in the best light possible--but best light doesn't mean unreal light.

They don't manage their social profiles. 

Employers Google candidates, but, as when checking references, many use a quick Web search as a final step. (Maybe checking out candidates online should be part of the initial screen?)

One of John's clients was about to be offered a job when certain photos popped up during a quick search. As the hiring manager for the financial services firm said, "How can I give this guy millions of dollars to manage after I've seen pictures of him doing ecstasy?"

Though some employers are certainly more tolerant (or understanding?) than others, for most candidates posting anything they wouldn't want their parents to see is simply too risky.

They dress inappropriately. 

"Inappropriate" can of course mean different things. For professional services, candidates should dress conservatively. Digital media can be less buttoned up but should still look the part. Dressing up is always safest.

Of course "dressing up" means different things to different people. To my early-20s daughter, dressing up means dressing up to go out. What she considers "dressy" would be juuust a tad inappropriate for a professional setting.

The key is for candidates to look the part--and to do that, that means they need to understand your company's culture.

They do no research. 

Employers typically Google candidates, but some candidates don't return the favor.

The hiring process is a two-way street: Interviewers want to see if the candidate is a good fit, and the candidate should be evaluating whether the company and the job is a good fit.

Why would you hire anyone who hasn't done everything to find out if he or she would love working for your company?

They ask no questions. 

Or, if they do ask questions, they ask "smart" questions in the hopes of making themselves look good.

For starters, here are five questions great job candidates ask. Another great approach that helps the candidate establish rapport while further evaluating the company is to ask relatively personal questions, like, "What part of your job is the most fun?" or "What makes you love working here?"

All the small-business owners I know focus heavily on cultural fit. They definitely evaluate skills, but they're also trying hard to select candidates who will help support and build the kind of business they and their employees will love working for.

In short, smart interviewers are looking for candidates who don't just want a job but a job they will love--and are working hard to find out if this job is the one.

Now it's your turn. What is the quickest way for otherwise great candidates to blow the interview? What are your biggest red flags?