On a day when every Brazilian, or so it seemed, was sharing protest pictures on social media, there was one picture that became the picture, the one everyone was talking about – a sort of Rorschach test for the country.

On Sunday, nearly two million people took to the streets in 121 cities across Brazil to protest government corruption and to demand the impeachment or resignation of President Dilma Rousseff, whose government is enmeshed in a massive graft scandal.

Among the people who went to march were Claudio Pracownik and Carolina Maia Pracownik, a white couple who live on a leafy street in Ipanema. They brought with them their little white dog, on a colour co-ordinated leash, and their two toddler daughters, who rode in a stroller pushed by a black maid wearing the all-white uniform that some wealthy Brazilians prefer their domestic employees to wear.

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Joao Valadares, a photographer with the newspaper Correio Braziliense, snapped their picture on the street in Copacabana, and before the protest was even over, it had been shared thousands of times – millions, by nightfall, here in this country that has the second-largest number of daily Facebook users.

Some Brazilians looked at the picture and saw a patriotic family, fed up with a seemingly unending series of revelations about politicians and kickbacks, on their way to make their voices heard – accompanied by a woman who has "an honest job", as a great many commentators put it, at a time when millions of Brazilians are unemployed.

Others saw the poster-couple for elite Brazil. "I look at this photo and I see primarily the repetition of a scene going back to the time of slavery," Deborah Thome, a Rio writer and political scientist, wrote on her Facebook page Sunday night. "I am disgusted by the sight of a nanny dressed in a slave-maid's clothes."

And that, she said, is emblematic of everything that's troubling about the current protests.

Polling suggests that Brazilians across all social classes and ethnicities are extremely frustrated with corruption and with the crisis currently paralyzing government. But they differ in where they apportion blame. The half-dozen large anti-corruption demonstrations in the past year have been dominated by white and upper-middle-class protesters, who tend to be supporters of the opposition Brazilian Social Democratic Party (PSDB), and to have little love for Ms. Rousseff's left-leaning Workers' Party, which has won four successive elections, the last one with a narrow defeat of the PSDB in 2014. Rousseff supporters say they are using the corruption scandal – in which politicians from virtually every party have been named – to try to unseat a democratically elected government.

The research institute Datafolha said that 77 per cent of participants at the demonstration in Sao Paulo, which was the largest in the country, were university graduates, versus the overall rate of 28 per cent in the city. Half of participants said they earned "between five and 20 times minimum wage," versus 23 per cent of people in the overall population who earn in this range; 77 per cent self-identify as white although the last census showed just 45 per cent of Brazilians are white.

It's a troubling moment for the country, Ms. Thome said. "The debate now –nothing will convince me otherwise – is between different and conflicting political visions. I don't support the protests, but like many friends who went to the street, I want a better country. But the paths we want to take to get there are very different. And, in most cases, those paths will not meet."

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But Joana Gryner, a Rio clinical psychologist who marched on Sunday, said she is frustrated by the suggestion that the Pracowniks have less right to protest than anyone else in this democracy.

"It's too harsh to say that a particular social group cannot protest," she said. "We have to stop churning out rules and dictating what is the correct way to protest. They were not hurting anyone, and plenty have done harm to them."

Ms. Maia Pracownik and Mr. Pracownik did not return calls from The Globe and Mail. But in a Facebook post of his own, he expressed disgust at what he called the violation of his privacy, saying a photo without context was being used as a "distraction" from the country's political and economic crisis. And he made a pointed reference to Lava Jato, the investigation into an alleged $2-billion (U.S.) contracts-for-kickbacks scheme at the state energy company Petrobras, in which many senior political figures, including former president Luiz Inacio Lula da Silva, are now implicated.

"I earn my money honestly," wrote Mr. Pracownik, who is the vice-president for finance at the Rio football club Flamengo. "My assets are in my own name, I don't get gifts from construction companies, I pay taxes (not bribes), I employ hundreds of people in my business and four more in my home. … Everyone gets paid on time. And everyone has a registered employment card and I pay social benefits for every one of them."

He said the nanny in the picture only works for them on weekends, and is paid extra because of it. "She is free to resign if she would prefer other work or another employer," he said. "I don't treat her like a victim, or as if she is a member of my family. I treat with respect and with the dignity that any employee deserves."

But in the furious debate about the photo, many have expressed scorn – at Ms. Maia Pracownik in particular – that she wasn't pushing the stroller herself, that she has a nanny even on Sunday. "You don't know enough to handle a baby carriage, but you think you can give your opinion on how to run a country," sniped an engineer named Francielle Soares in Sao Paulo.

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Others expressed disapproval that employers would take their nanny to a political demonstration. But that part came as no surprise to the nannies watching over toddlers in a childrens' park near the family's apartment on Monday. "She's working, right?" said one of the women – none was willing to be quoted by name talking about their jobs. "She's obliged to go – she's earning, so it's her responsibility to accompany the parents wherever they want to go."

Brazilians, who are deft and fast with memes, reposted the picture with a thousand snarky captions, such as "Speed it up, there, Maria [the generic 'maid name'], we have to get out to protest against this government that made us pay you minimum wage."

Brazil's economic crisis has seen a huge spike in unemployment – 1.5 million jobs were shed in 2015 and another 2.2 million are expected to be lost as the contraction continues this year. For many women who had new pink-collar positions in the economy that boomed under Mr. da Silva, that has meant a reluctant return to domestic work, traditionally the chief occupational sector for women of colour in Brazil.

When the picture began to be shared with scornful comments, some domestic workers wrote their own comments, pointing out they would be glad to have the job. "What's the problem?" wrote Marcela Margiotta on the popular Facebeook site Humans of the Protest. "I'm going crazy looking for a job to work on weekends. … Thank god there are nanny jobs out there, because these days you graduate and then, surprise: there are no jobs!"