YOU HEAR IT all the time. There's plenty of work out there, but a lot of people just don't want to work. They'd rather live off welfare. They're lazy. Just look at all the want ads in the paper. There are endless jobs going begging out there, millions of them. There's work for anyone who wants it.

Sure.

Okay, let's look at all those want ads. Specifically, let's look at the ads for one recent Saturday in The Washington Post, stacks of little ads in search of drivers or restaurant managers or clerks or carpenters, almost anything you can name. Plenty for everyone, right? Wrong. Follow the trail of those ads and, aside from learning about the nature of work in Washington, you discover the flaws of that old argument, why it doesn't hold up.

Certainly there are some jobs out there that go begging. Jobs for clerical workers are not always easy to fill in this "paper city," where the clerical work force is hard pressed to keep up with the pace at which the paper is churned out.

But for the hardest core of unemployed, jobless workers with no skills and next to no education, the number of jobs available doesn't come close to matching the number of people desperate to have them.

At first glance, the ads on a Saturday morning in February looked deceptively promising, 1,059 notices of dreams and opportunity (not counting those in a separate category for domestic help), a richly stocked bazaar for job hunters.

But you soon learn that the jobs advertised, just those in the paper, are nowhere near the number of people unemployed. On that same day, according to the most recent unemployment figures, 77,600 people were out of work in the Washington metropolitan area - more than 70 times the 1,059 jobs listed.

For the legion of hard-core jobless in particular, the least employable among the, 77,600, those ads generally are not signs of the American opportunity machine at all. For people in that category, wading through the want ads is akin to unwrapping a large, elaborately wrapped present, only to discover another smaller box inside, a still smaller box inside that, and most likely nothing in the end.

For the few jobs available, a mass of applicants rush in to try to fill them, according to the people who placed the ads that day. "I get people who call me every single day, pleading with me," said one man who occasionally advertises for unskilled help.

The Middle-Class Look.

THE SITUATION is markedly different, of course, for clerical jobs, the backbone of the area's economy. Just as Houston offers almost unlimited opportunities for refinery workers, Washington holds out jobs and promise for people with cerical and secretarial skills. Nearly a third of all the jobs in the area are clerical, jobs for secretaries, bookkeepers, cashiers and others.

"When I moved here, they told me that if I could type, I could get a job," said one young woman who moved to Washington from Delaware. That's true, according to employment officials, who say they can always find a job for someone who types.

"If you've got the ability, you can pretty much ask for anything you want," said Chris Barnhart of Progressive Plastics, who had placed an ad for a secretary. In contrast was the company's experience with an ad for factory workers. "We must have had 40 to 50 calls," said Garnhart. "They can't be as selective."

The solution seems simple: Teach the unskilled to type. The problem is that the unskilled frequently can barely read and write, a major barrier to acquiring the skills that might make them employable. Another problem is that employers looking for secretaries are frequently looking for people who look, act and dress middle class.

"Most of the applicants didn't qualify," said one woman who advertised for a receptionist-typist. "Either they couldn't type or could type and couldn't do anything else," said Betsey Bailey of Midwest Telecommunications. "They didn't speak well or have the right attitude."

Other employers said they eliminated from consideration for clerical jobs callers who didn't speak grammatically or who spoke with a foreign accent.

Looking closely at the ads printed that Saturday eliminated most of them as full-time jobs for the hard-core unemployed. There were 64 jobs that were part-time or temporary. Next were 29 that required the job holder to move and live on the jobs site - jobs such as apartment manager.

Fourteen of the 1,059 ads were not even real jobs but come-ons for real estate courses, repeats or, in one case, a misplaced advertisement for vacuum cleaners for sale. Another 16 advertised jobs in areas ranging from Baltimore to Israel.

At least 30 more jobs were not salaried but were for commission only or required an investment by the jobseeker, such as purchase of a tractor-trailer or a distribution route. That left 906 jobs.

In other words, while there were 77,600 people out of work in the metropolitan area, there were 85 times as many people out of work as there were jobs left after these subtractions. Morever, there were at least 19,000 underemployed persons, those looking for better jobs, who might have been candidates for the realtive handful of jobs advertised.

"The Kids Need Food"

OF THE 906 jobs left, 157 advertisements were for managers, professionals or technicians. Somewhere out there jobs were waiting for architects, engineers, a choir director and an elementary school principal. Still another 223 jobs advertised were for skilled craftspeople, such as carpenters, mechanics and electricians. Taken together, those categories accounted for more than 41 percent of the jobs advertised.

Eliminating another 25 jobs that required some type of license, such as a beautician's license, and 245 clearical jobs (the largest category advertised), left 256 jobs for the truly unskilled and undereducated job hunter.

According to those offering these jobs, the advertisements produced a large number of applicants, many of them anxious to work. For most of the jobs, however, several prospective employers said, there were also applicants whose only interest in applying for the job appeared to be to claim to have done so. Demonstrating active pursuit of a job is a condition for drawing unemployment compensation.

Sandy Morse, manager of Chambers Flowers, was looking for an assistant manager for the wholesale flower operation, a job he filled less than a week after the advertisement appeared. There were about 20 applicants for the job, he said. When he advertises for drivers, however, he often gets as many as 100 responses.

It was Morse who reported the daily, pleading phone calls for those jobs. "They say things like, 'I'm out of work,' and, 'The kids need food,' " he said. Morse said that he wished he had enough jobs to give them. "I'm easily touched," he said.

An advertisement for a hostess for a Howard Johnson's restaurant drew about 50 responses. "It seems as if an awful lot of people in D.C. are out of work," said the woman who took the calls. "I think a lot of people are getting fairly desperate."

Gerard Gasquet, general manager of a restaurant, The Bread Oven, got about 40 applicants when he advertised for a pastry apprentice. The job pays $4 an hour and requires the apprentice to start work at 5 or 6 a.m.

Gasquet said he found "a lot of people really wanting a job who can't get one. It looks like the market is not so open for people wanting to work."

In calling advertisers over a period of weeks, I successfully contacted 109 who had advertised for help. Of the employers reached, 79 percent had filled the jobs they advertised within three weeks, even though in the first two weeks after the advertisements appeared the weather discouraged job hunting. The first week was extremely cold; the second, Washington was paralyzed by a major snowstorm. Most of the jobs that were filled were taken during the first week.

Clearly the largest selling effort was in advertisements seeking clerical help. Ads for secretaries rang with phrases intended to make the job sound attractive. "It you like people and enjoy working in a warm and congenial atmosphere," began one. "Pelasant work environment," "congenial atmosphere and good benefits" and "interesting diversified work in Cap. Hill location," promised others.

Of the jobs that were not filled when I called, 52 percent were clerical jobs.

No Kitchen Jobs

THE JOBS advertised in The Washington Post that day were only a portion of the jobs actually available. Many professional jobs are filled by word of mouth. So are jobs in parking lots and restaurants, according to Earl Lee, an occupational analyst at the D.C. Department of Labor.

"We don't get the kitchen jobs that we used to because a lot of illegal aliens fill those jobs and they tell one another," said Lee. A number of foreign students fill parking lot attendant jobs and pass on those jobs by word of mouth also, he said.

The D.C. job bank, which is used by employment services in all the area's jurisdictions, generally lists from 3,500 to 5,000 jobs daily. The District's manpower officials have found the same general trends in response to the jobs listed in the job bank that were apparent in the response to The Post's ads.

"As a rule, we know that the jobs that require little experience or no experience go very quickly," said Smith. "If the job requirements are low, generally the same day it is listed it's filled," he said. With clerical jobs, "if they want higher typing speeds than 60 words per minute, those jobs will remain on the books."

"There is a big structural unemployment problem in this area," said John Gallahan, a labor economist for the District of Columbia. "The people that are unemployed don't match up with the jobs that are available," he said. "There are skilled jobs available that an awful lot of the unemployed don't have the skill to fill."

In several cases where jobs advertised in The Washington Post went unfilled, the job interviewer or employer said he or she believed that the job paid too little to be attractive.

"We've been running that ad for three or four months" with no response, said Alek Beri of an advertisement for a helper for an iron works. The job paid $3 to $3.50 an hour, he said. "At $3 an hour, I imagine they can get unemployment equal to that amount."

A 40-hour-a-week job that pays $3 an hour produces an annual income of $6,240, just slightly over the $6,200 that the federal government has defined as a poverty-level income for a non-farm family of four.

A minority of employers interviewed felt that the area's jobless men and women simply didn't want to work. "There are a surprising number of people who are out of work, yet when you put an ad in, you can't get someone," said a dress shop manager. "People don't want to work for their money. They like to collect unemployment."

"The response to our ad for help wanted was disappointing," said another woman who talked to applicants about a $7,500 receptionist/clerk typist job. "I thought there were a lot of people out there looking for work. I think our Washington job market is the laziest thing that's happened."

That wasn't what Mony Toueg, that manager of a camera shop, found when he advertised for a $3-an-hour photo-finishing clerk. Before he hired one, he talked to about 10 applicants. Most were not qualified, Toueg said. They were "people who just wanted anything. They just wanted to be there to have work." CAPTION: Illustration, By Joseph Bolman for The Washington Post; Graph, What the Want Ads Offer, The Washington Post