RIO DE JANEIRO — The Blowfish’s Den was a mess. The tables were crowded with empty bottles, dirty plates were stacked up and the bathroom had run out of soap.

In the corner, the bar’s owner, Marco Antônio Targino, was eating a plate of fried pork cracklings. “For those who like filth,” he said with a smile, “this here is a beauty.”

Out front, the cobblestone alley was packed with unmasked revelers, swaying and singing around a makeshift samba band. It was the biggest crowd since the start of the pandemic, and Mr. Targino was soaking it all in.

“It feels like I’m alive again,” he said. “I didn’t die.”

Neither did his bar. The pandemic lockdowns and lost sales nearly killed the place, and the hundreds of drinking spots like it. But now, in one of the clearest signs that Rio de Janeiro is returning to something like normal, the city’s “dirty feet” are back.

That’s the name for the hole-in-the-wall joints that spill out onto Rio’s sidewalks with plastic tables and chairs, offering cold beer and something fried at almost any hour of the day. Known as “pé sujo” in Portuguese, a dirty foot is a cross between a dive bar and a greasy spoon, where the grit and grime are part of the charm. The countertops are rusty, the prices cut-rate, and shoes and shirts often optional.

“The big restaurants don’t let you smoke. Here you can smoke almost anything,” said Sandro Lima Rodrigues, a bald, goateed server at La Paris, a dirty foot where a breakfast of espresso and grilled bread smeared with processed cheese costs 90 cents.

“We’re the essence of Rio,” he added.

Yes, Rio de Janeiro has golden beaches, breathtaking views and its colorful Carnival, but many Cariocas, as its residents are known, agree that to discover their city’s spirit, you need to experience a dirty foot.

“Rio is not a democratic place,” said Marcelo Freixo, a history professor who now represents Rio in Brazil’s Congress. “But you can escape that inequality in a few places: the sambas, the beaches and the dive bars.”

The pandemic forced a quarter of Rio’s restaurants and bars to close, according to a local trade group, and the city just set new rules restricting the unvaccinated from entering bars amid concerns over the Omicron variant. Yet, in a relief to many Cariocas, most of the dirty feet are still going strong.

Fernando Blower, a Rio bar owner who runs the trade group, attributed their resilience to the fact that many are family-run operations that got creative.

The Blowfish’s Den, or Toca do Baiacú, sold art donated by a well-known cartoonist who regularly drinks at the bar. La Paris opened when the police weren’t watching and sold takeout beer when they were. Confectionary and Bar Solange (that’s one bar, and no, it doesn’t make candy) hand-delivered plates of beef ribs and liver to its neighborhood regulars. All three kept paying their employees through the lockdowns, even without government assistance.

The Senate Warehouse, or Armazém Senado, sold toothpaste, toilet paper and bleach. The two brothers who own the place took out a roughly $5,000 loan and then restarted their samba nights at a time when the city still restricted gatherings. (Their decision made headlines when the mayor showed up — and was photographed singing without a mask. He paid a fine.)

Mr. Targino, 64, first began drinking at what would become the Blowfish’s Den in the 1980s after days working as a banker nearby. Over cheap beer and cachaça, he befriended the other regulars, including a local boat mechanic.

In 2007, the bar went up for sale. Worried it would turn into another gentrified restaurant, he bought it and renamed the place after a longtime waiter who he said resembled a blowfish. He sketched a new logo on cigarette papers: an overweight, beer-drinking fish.

“It was really filthy,” Mr. Targino said. “Deplorable. A latrine.”

“Now it’s just a mess,” he said.

To clean up the place, Mr. Targino hired the boat mechanic, Geraldo Serrador. Now the bar’s janitor and handyman, he did not appreciate his boss’s description of its hygiene.

“I’m worried right now there’s a dirty glass in the kitchen,” Mr. Serrador, 61, shouted over a samba band.

Dirty feet are close siblings of other types of casual bars, the boteco and botequim, which started as corner stores and derive their name from “bodega.”

The origins of the term “dirty foot” aren’t so clear. Some bar owners attribute it to poor clientele who wore only sandals or lacked shoes. Others said it was because customers used to spit on the floors, which the bars would clean with sawdust.

“You came out of there with your feet dirty,” said Paulo Mussoi, a Rio journalist who has written a column about dirty feet for more than 20 years using the pen name “Juarez Becoza.”

For decades, the bars were mostly for working-class men. Many even lacked women’s bathrooms. But in the 1990s, Rio’s middle class discovered dirty feet and boteco, and they quickly became fashionable, celebrated as hidden culinary gems.

The food in dirty feet bars shows influences from Portugal, West Africa and Brazil’s Northeast. There are fried sardines, pickled eggs, gizzards and stews made from cow’s feet and oxtail. The bars have inspired imitators that mimic their low-key style but with higher prices. Cariocas call them “clean feet.” (It’s an insult.)

Your average dirty foot is a neighborhood hangout that reflects the rhythms of Rio life. Take Confectionary and Bar Solange, in a residential section of Rio’s middle-class Gloria neighborhood, south of downtown.

Pelé Joensson, 57, a Swedish immigrant, said he arrives most days around 6 a.m. to buy coffee and carry one of the bar’s plastic chairs across the street to watch his neighborhood wake up. He then spends hours socializing.

“If you live alone, this is where you have your social life,” he said.

By late morning, a waiter and cook known to everyone as “Toninho,” or Little Tony, put out fresh pork stew ($3 a plate.) Three construction workers on break leaned against the other end of the bar, sipping soda. Hours later, neighbors celebrated a local doorman’s birthday with cake and a raffle for frozen cod.

By nightfall, the scene got louder. Customers pulled the flimsy plastic chairs from a stack by the door and added them to widening circles of friends. Each group shared one 20-ounce bottle of beer ($1.40) at a time, split into small glasses. The approach is designed to keep anyone from drinking warm beer, sacrilege in Brazil. The bottles sit in snug coolers known as “little shirts,” which, in Portuguese, is slang for a condom.

One particularly boisterous group included a taxi driver, a real estate agent, one of the first transgender executives at Unilever, and a retired salesman in leather pants.

“What makes a dirty foot?” asked the real estate agent, Luiz Felipe Cavalcante. “Beer, food, people, friendship, soccer. Oh, and women, women!”

Aparecida Araújo, a cement saleswoman, chimed in with another missing ingredient: “Drunks talking nonsense.”

Mr. Targino, the Blowfish’s Den owner, said that what defines a dirty foot is not its food or drinks, but its laid-back ethos.

“If you take a pig, bring it into your house, bathe it, put a bow around its neck and leave it in your backyard, what’s it going to do? It’ll throw itself in the mud and get dirty all over again,” he said. “I want to go where I feel good, have my shirt open and wear flip flops. That’s where I’m in my natural habitat, just like that healthy little pig.”

Breno Salvador contributed reporting.