The factory manager of the Landmark Plastic Company in Akron, Ohio, once told me that he was so concerned about high turnover among workers that he began holding exit interviews to find out why they were leaving. The answers surprised him. It wasn’t the meager pay, the noise, the mind-numbing assembly lines or the mist of plastic dust in the air. Instead, most employees complained “that they didn’t feel needed, necessary or wanted,” the manager reported, and were treated like “just another body.”

Linda Tirado will not be amazed to read this little anecdote, because the craving for personal dignity is a force that drives her caustic commentary, “Hand to Mouth.” In the low-wage jobs where she has worked, bosses don’t ask subordinates what they think. Humiliation is the rule. “Poor people” are dehumanized by “rich people” wielding contempt and hypocritical moral judgments across a stark divide. The society she portrays is bipolar, with practically nobody between wealth and destitution.

This is a caricature, of course, but if you go along with her, as you do with a political cartoonist or a stand-up comedian, you will learn a lot about life at the bottom of America. She puts her anger to good use.

Few working poor have the luxury of indignation. Enervated by swing shifts, cash shortfalls and too little sleep, they are badgered by the American creed that anyone who works hard can prosper, and many internalize the belief that those who don’t prosper are themselves to blame.

Not Tirado. She is refreshingly infuriated. She acknowledges her faults, but she hones a constructive resentment to cut through her chronic depression, sharpen her wit and tune her X-ray vision into the disparities of power and money. She maps the chain reactions that lead families from one setback to another.

It’s rare to hear directly from the poor. Usually their voices are filtered through journalists or activists. So Tirado’s raw clarity is startling. It’s nice to imagine her ranting to a class of stunned M.B.A. candidates who are preparing to employ people like her; they would learn how denying dignity corrodes attitudes toward work and authority. In her world, medical practitioners are condescending and preachy, caseworkers are cruelly imperious, government systems are Kafkaesque and the downward spiral at the workplace is defeating.

“I wouldn’t even mind the degradations of my work life so much if the privileged and powerful were honest about it,” she writes. “Instead, we’re told to work harder and be grateful we have jobs, food and a roof over our heads. . . . We are. But in exchange for all that work we’re doing, and all our miserable work conditions, we’re not allowed to demand anything in return. No sense of accomplishment, or respect from above or job security. We are expected not to feel entitled to these things.”

Some workers have to ask permission to use the bathroom. Some are searched as they leave for home. Tirado was expected to change shifts on such short notice in one part-time position that she couldn’t hold a second job.

“The result of all of this? I just give up caring about work,” she writes. “I lose the energy, the bounce, the willingness. I’ll perform as directed, but no more than that. I’ve rarely had a boss who gave me any indication that he valued me more highly than my uniform — we were that interchangeable — so I don’t go out of my way for my bosses either. The problem I have isn’t just being undervalued — it’s that it feels as though people go out of their way to make sure you know how useless you are.”

Mental engagement seems unwelcome by management. “Nobody is interested in our thoughts, opinions or the contributions we might be able to make — they want robots.” Yet customers are annoyed when workers “zombie out to survive,” she notes. “Next time you see someone being ‘sullen’ or ‘rude,’ try being nice to them. It’s likely you’ll be the first person to do so in hours. Alternatively, ask them an intelligent question. I used to come alive when someone legitimately wanted to know what I’d recommend.”

Stress over money and the exhaustion of working multiple jobs aren’t “great for higher cognitive activity,” Tirado notes, leaving her hungry for intellectual stimulation. “I stopped thinking in higher concepts, gradually. I feel stupid when I realize how long it’s been since I thought about anything beyond what I had to get through to keep everything moving along: no philosophy, no music, no literature. We know we’re not at capacity, and it rankles.”

There are coping mechanisms. Some like booze and drugs. She likes sex and smoking. “The chemical rush of sex is a great way to forget about your problems for a little while,” she says, and “sex is completely free.” Smoking is harmful, she concedes, but “it’s a stimulant. When I am too tired to walk one more step, I can smoke and go for another hour. . . . I feel a little better, just for a minute.”

As for the self-righteous rich, “You guys look pretty ridiculous talking about our drug and alcohol use while swanky rehab centers are doing a thriving business,” Tirado writes in an “open letter to rich people” toward the end of her book. She delights in busting stereotypes of the poor with sassy, profane invective, and humor that sometimes works. It would be fun to watch her debate Representative Paul Ryan, who leads the Republicans’ campaign to blame the victims of poverty.

She does her own stereotyping, though — of the “rich” as a vast class of nonpoor with titanium strollers, tutors for their 3-year-olds and opinions that seem straight out of Fox News.

So much obscenity laces the book that it won’t be assigned by high school teachers worried about prudish parents, and that’s a loss. Her favorite adjectives and adverbs may fit into locker-room conversation, but in print, after many repetitions, they read like casual substitutes for a well-crafted phrase.

Tirado’s credibility would have been helped by a coherent paragraph or two of autobiography instead of the disjointed fragments scattered throughout the text. Once assembled, they form a typical mosaic of someone moving in and out of poverty — falling from a middle-class childhood, dropping out of college, doing at least one stint as a manager of a fast-food restaurant and receiving belated family help to buy a house, but also depending at times on food stamps and Medicaid as her husband, an Iraq veteran, failed to get a promised V.A. stipend.

After an online essay she wrote went viral last year and she raised over $60,000 on the web, conservative pundits seized on bits of her story to accuse her of not being truly poor. Not perpetually poor would be more accurate, but that doesn’t disqualify her as a participant-observer. Stepping back at times gives her perspective for acute insights and pleas for empathy.

“There are poor and working-class people everywhere, guys,” she writes in her afterword. “You can just have a conversation with one, like a real human being. Give it a try. You’ll like it.”