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Registered Nurse Tung Tran hangs an I.V. bag for a patient at the University of Miami Hospital's Emergency Department .

Hot-job lists tout occupations with endless positions to be had in a host of professions. But in reality, these lists can be meaningless when it comes to ultimately landing a job.

I’m stressing this today because every time we run studies on growth occupations — done by private companies and the government — we get a flurry of comments from readers about how some of the so-called hot jobs aren’t hot at all. Some of you are unable to find jobs or good pay in the professions these lists extol as booming, and others were laid off from these supposed growth gigs.

Here’s a sampling of comments we got after a story ran Wednesday on the 10 hardest to fill jobs, including everything from nursing to skilled trades: 

“My son has been looking for a decent machinist position since he got out of college,” wrote Old Dad.

And HookedOnSprockets, a skilled construction worker, noted: “I laugh at the people who call me; they are desperate for workers but unwilling to pay fair wages.”

A question I posed on Twitter about whether hot-job lists were bogus was largely met with yeas. This tweet is from seasoned college recruiting expert Sharon Wiatt Jones, aka @WiattJones: “Yes, they often include college professor. Only about half finish Ph.D. and tenure track positions declining fast.”

Indeed, just because a job is labeled hot, doesn’t mean you’ll find a plethora of jobs where you live, or a fat paycheck. And even if there are lots of jobs that need filling, that doesn’t mean an employer will hire you, because maybe you don’t have the exact experience, or you may be a victim of age discrimination, labor experts stressed.

“There are many factors that go into each individual’s probability to find a given job,” said Enrico Moretti, an economist at University of California, Berkeley, and author of “The New Geography of Jobs.”

Moretti believes the availability of jobs is largely based on geography.

“There are vast differences across cities in the types of jobs available,” he explained. “Hot-job lists might give you an average, but what really matters is where you live. Like the latest unemployment numbers, which were pretty disappointing, but if you look at some regions, or cities, they are actually doing well.”

Another factor is the ever-changing landscape of job opportunities. A shortage in one particular occupation today could end up being a glut tomorrow.

Case in point: nursing. For years, we wrote about reports predicting an impending nursing shortage, and that prompted many people to head to nursing school.

Now, things appear to have turned around. An April report in the New England Journal of Medicine titled “Registered Nurse Labor Supply and the Recession — Are We in a Bubble?” by professors at a number of universities found:  “The decade-long national shortage of RNs appears to have ended.”

That doesn’t mean this will be the case a decade from now. The researchers pointed out that:

Over the next several years, many RNs who entered the work force during the economic downturn are likely to leave their jobs once the economy recovers. Yet because there is no empirically based understanding of how recessions affect transitions into and out of the RN work force, employers and work force planners are unable to anticipate how many nurses might choose to leave the work force once a robust jobs recovery begins.

This shows how volatile any occupational prediction can be, and how economic twists and turns can turn today’s hot job into tomorrow’s not job.

In many of the so-called hot business professions, for example, offshoring of jobs has been a source of pain for workers and those wanting to get into these professions and make good money.

A recent report by the Hackett Group on offshoring showed that by 2016 an additional 750,000 IT, finance, and other business services jobs will head to India and other countries where wages are lower than here.

But, the report added, “additional offshoring in these areas will begin to decline by 2014, and in the next eight to 10 years the flow of jobs offshore is likely to cease, as companies simply run out of business services jobs suitable for moving to low-cost countries.”

Clearly, it’s hard to know on what to base a decision to pick a major, get more schooling or change careers. 

The most detailed national projections on occupations come from the Department of Labor’s Bureau of Labor Statistics' Occupational Outlook Handbook. Indeed, many of the top-job lists out there are based on this exact BLS data. 

The report, however, wasn’t created for people looking for an occupation to get into in the near term.

“It was created for high school students to give them an idea of skills and types of jobs that will be available for them,” said Gary Steinberg, a spokesman for the BLS. “It matches their interests with what’s out there in the workplace in 10 years.”

The BLS does have a great deal of data on job openings right now based on industry, he noted. 

But he cautioned that the data the BLS provides shouldn’t be used as a career decision be-all and end-all. “It’s one piece of the total picture,” he said. “It’s guidance and help for people looking at a career change or to know something about an occupation.”

So don't just use a list to make expensive decisions, such as whether to sign up for job training.

"Unless you are already trained in the area or are already in the process of being trained, the job prospects eventually turn scarce or the pay drops significantly due to an excess supply of newly qualified candidates, many of whom are now strapped with debt from getting the training needed," advised Kevin Burns, director of the undergraduate business career center at the W.P. Carey School of Business at Arizona State University.

"The only group that really profited was the institution that sold  the training," he continued. "Be very careful about jumping at a hot job that requires significant debt. Do the math and make sure that the long-term earnings are significantly greater than the debt plus interest required."

If you want to figure out what the hot jobs are nationally or in your region now, Moretti suggested going right to the bottom line: Wages paid for particular positions. (The BLS offers this information nationally and by state available online.)

“If you’re willing to move, look at geographic areas that pay the most; if you aren’t willing to move, look at your own area.”

But, he added, moving may be your best option if you really want to take advantage of growth occupations now.

“The difference in earning potential among American cities is the largest it’s been in 30 years,” he said, adding that as a result, “the return for mobility is larger than it’s been in 30 years.”