A local Little League baseball game is heating up under a hazy summer sky. Doting mothers fuss over their sons' dingy caps and mud-streaked jerseys.

Why, they wonder, is Johnny’s uniform always so clean and bright?

Johnny’s mom tells them she used to scrub his baseball uniform relentlessly after games — but nothing worked. Until, she says, she discovered Miracle Brand X detergent.

"You should try it," she urges. "Trust me — you’ll be sold."

"Miracle Brand X," her friends repeat. "We’ll have to remember that."

Little do they know Johnny’s mother is a paid, undercover advertiser.

Call it this millennium’s version of product placement — which has gone beyond TV shows and movies and infiltrated the real world.

Marketing firms specializing in so-called "buzz" tactics have eked a growing business out of the belief that people like those Little League moms will remember — and buy — what their peers are raving about.

'It Could Be Your Mother'

"The person delivering that message, rather than being some superstar, is the average Joe," said Jonathan Ressler, president and CEO of one such New York City marketing firm, Big Fat Inc. "It could be your friend. It could be your mother, for all you know."

Companies like Big Fat are so convinced of the impact of word-of-mouth advertising they hire people across the country — including Little League mothers and bar patrons — to underhandedly spread information about a product without revealing they’re paid endorsers. The firm targets the 18-to-34-year-old set, primarily: those watching television commercials through sometimes-cynical eyes.

Big Fat is getting a lot of buzz itself these days for cultivating its secretive spread-the-word strategy into an art form.

Sometimes the offbeat firm sends teams of young, chatty hipsters into trendy bars to talk up, say, a flavored water as the perfect mixer in a cocktail. "It's low-cal," the friends will tell women enthusiastically. "It hydrates you — so you won't get a hangover," they'll say to guys.

Other times, the company slips employees dough to drive a sleek, cutting-edge car or wear a funky new line of clothing for product visibility. In one campaign, Big Fat paid apartment-building doormen to keep empty boxes bearing the name of an Internet retailer at the front desk, in the hope tenants would be subliminally influenced. And it worked, according to the company, which claimed the retailer's sales spiked as a result.

"Everybody says word-of-mouth is the most powerful form of advertising. It is," Ressler said. "We’re creating that word-of-mouth. We give these brands a way to be chosen."

Big Fat, which has 45 marketing managers in 30 U.S. cities, also uses overt marketing campaigns to promote products. Its clients include Nestle, Pepsi-Cola Co.'s FruitWorks, Volvic water, USA Networks and Brown & Williamson Tobacco. The firm considers the under-the-radar schemes only one element of its business.

Those who work incognito to promote Big Fat’s clients are paid up to $500 for a gig, according to Chief Strategy Officer John Palumbo. Some are so enthusiastic about the brand they’re hyping, he said, they’ll do it for nothing.

"People end up experiencing the products," Palumbo said. "We want people talking about a brand without knowing they’re talking about it."

"Leaners" — patrons who lean across a bar to order a drink by brand name and then offer a tidbit about the product to those around them — and "key influencers" — bouncers, bartenders and others in visible positions — might do the surreptitious promoting. Strategists also use the "request" tactic: sending teams into a store over a period of time to ask for a brand it doesn’t carry until finally owners are pushed to stock their shelves with it.

The company chooses undercover agents using screening surveys and, of course, word-of-mouth. Team members must sign confidentiality agreements promising they won’t talk about what they do.

Ethical Buzz

Palumbo and Ressler insist their practices are legal — and ethical.

"I don’t think we’re doing anything wrong," Palumbo said. "We look at it as creating a friendship between a target and a brand."

Ressler said they aren't misleading anyone.

"We give you information and let you decide," Ressler said. "If it doesn't fit into your life, you're not going to buy it. We ultimately can't control consumer behavior."

Not everyone agrees.

"Is it illegal? No. Is it unethical? Sort of," said Advertising Age reporter Richard Linnett. "To fully inform your audience has always been a part of the ethics of advertising. This is not fully informing them. It’s like sneaking one in through the back door."

Though buzz marketing has also raised eyebrows at the Federal Trade Commission, a spokeswoman said the agency has no plans to bring legal action against Big Fat or similar firms.

"It’s troubling, but whether it rises to the level of being illegal is not clear," said Mary Engle, assistant director of the FTC’s advertising practices division. "At a minimum, it’s not clear that there’s enough harm done to make it a priority for the FTC."

So next time you meet a friendly, fellow parent at your child's game or a groovy guy or girl at a bar, think twice if talk turns quickly to a product you can't afford to miss. Reality advertising has arrived.

"The whole world is a commercial," Advertising Age's Linnett said. "We're all walking, talking brands."

Fox News' Erik Liljegren contributed to this report.