NEW YORK --- A resume and a brief job interview can't answer the question that matters most to a new hire's co-workers: Is this person an absolute pain?

Despite a labor shortage in many sectors, some employers are pickier than ever about whom they hire. Businesses in fields where jobs are highly coveted -- or just sound like fun -- are stepping up efforts to weed out people who might have the right credentials but the wrong personality.

Call it the "plays well with others" factor.

Job candidates at investment banks have long endured dozens of interviews designed, in part, to see if new hires will get along with everyone they'll work with. Whole Foods Market Inc. holds group interviews, in which people who will work under a manager are part of the team that grills candidates and collectively picks hires.

"In this bloggable, cell phone camera world, your brand on the inside is going to be your brand on the outside. If you have a bunch of jerks, your brand is going to be a jerk," said Tim Sanders, former leadership coach at Yahoo Inc. and author of The Likeability Factor .

With the national unemployment rate low, at 4.7 percent, and the Baby Boom generation heading into retirement, employers from Microsoft Corp. to rural hospitals are worrying about finding enough workers. But companies such as Rackspace Managed Hosting are working hard to find reasons to turn people away.

Job interviews at the San Antonio company last all day, as interviewers try to rub away fake pleasantness.

"They're here for nine or ten hours," CEO Lanham Napier said. "We're very cordial about it. We're not aggressive, but we haven't met a human being yet who has the stamina to BS us all day."

There's a possible downside. In a Harvard Business Review article titled " Fool vs. Jerk: Whom Would You Hire?" Tiziana Casciaro of Harvard and Miguel Sousa Lobo of Duke University point out that people generally like people who are similar to them, so hiring for congeniality can limit diversity of opinions.

That's not the worry at Lindblad Expeditions, a 500-employee adventure cruise company.

Kris Thompson, the vice president of human resources, said, "You can teach people any technical skill, but you can't teach them how to be a kindhearted, generous-minded person with an open spirit."

In the mating dance of job interviews, employers traditionally put their best feet forward, too, trumpeting their wonderful benefits packages while leaving out the bit about working late.

Not Lindblad. It sends job applicants a DVD showing not one, but two shots of a crew member cleaning toilets. A dishwasher talks about washing 5,000 dishes in one day.

"It's meant to scare you off," company founder Sven Lindblad said.

After watching the DVD and hearing an unvarnished description of life onboard a Lindblad ship, the majority of applicants drop out, Ms. Thompson said.

New hires "undergo a drug test, a physical exam, they have to pack up their life, we buy them a plane ticket and outfit them with hundreds of dollars in uniforms," Ms. Thompson said. "If they get on board and say, 'This is not what I expected,' then shame on us."

At KaBoom, a nonprofit that builds playgrounds, the board was hammering co-founder and CEO Darell Hammond four years ago over the organization's high employee turnover.

"I rationalized that they were on the road too much, when in reality, it was the wrong fit in the wrong role," he said.

He started thinking about who left and why, then focused on the characteristics of workers who stayed.

His team kept a closer eye on job applicants in the reception area, which is set up as a playground, to see how they acted around playground equipment.

"If you're early, you may have to sit on a swing or the bottom of a slide," Mr. Hammond said. People who stand with a tight grip on their briefcases aren't asked back.

KaBoom sends prospective project managers to one of its four-day playground building trips, with the actual build on the last day involving 200 to 300 volunteers, many of whom have questions for KaBoom staff.

"If they're not easily approached, or they're easily stressed -- this is the way we find out and they find out if it's not going to work," he said.