NEW YORK - This Easter, Walmart Stores aired a television commercial promoting its Ad Match Guarantee. In it, an exuberant clerk touted the policy's benefits to a shopper named "Janette" from Lithonia, Ga.

"That price?" he said, pointing to an advertising circular the woman had brought in. "Walmart will match it right at the register. Yeah, and you don't even need your ad!"

Price-matching has become a key marketing tactic for retailers from Walmart to Target Corp. to Toys "R" Us Inc. as they try to attract shoppers amid an uneven U.S. recovery.

It's a risky strategy because the programs are difficult to manage - discretion to match or not is often left to store workers - and shoppers can complain if they don't get the deal they're expecting. In February, Toys "R" Us agreed to review its ad strategy after a consumer complained to an industry watchdog that workers didn't understand how the price-matching policy worked. At Bentonville, Ark.-based Walmart, according to interviews with workers and shoppers, the Ad Match Guarantee is inconsistently applied from store to store.

Robin Sherk, a New York-based analyst at consulting and research firm Kantar Retail, said Walmart is especially vulnerable because its lower-income customers are more likely to price-match than Target shoppers.

"Shoppers can get confused," she said. "They go to different stores and there are different policies - even in the same store, if you go to different cashiers."

Deisha Galberth Barnett, a Walmart spokeswoman, said: "It's unfortunate that there's a couple stores that aren't executing our match the right way. Based on data that is representative of stores across the country, it's not a national problem."

Price-matching programs vary widely from retailer to retailer. Best Buy lets customers match prices if the rival store is within a 25-mile radius. Walmart allows managers to define the size of their trade area because they are more attuned to local conditions "than anyone" at headquarters, Barnett said.

Store workers sometimes don't understand the rules. The Advertising Self-Regulatory Council's National Advertising Division, which investigates claims made in national advertising, found Toys "R" Us workers didn't know how to implement the retailer's price-match guarantee.

The probe began in December after a shopper who wanted the store to match an online price for a dice game complained that several clerks gave him different interpretations of the policy, according to a copy of the case. A large sign in the store said: "Spot a lower advertised price? We'll match it."

The National Advertising Division recommended that Toys "R" Us either "discontinue its overly broad claim" or post the limitations. The chain said it would review the strategy.

Toys "R" Us, based in Wayne, N.J., would not comment.

Whether or not price-matching issues are systemic, companies "should still be correcting them," said C. Lee Peeler, the council's president and chief executive officer.

Walmart has promoted its "simplified" Ad Match Guarantee in national ads since 2011, when Chief Merchandising Officer Duncan Mac Naughton said the company was determined to provide low prices "backed by a clear, consistent ad-match policy," according to a news release.

While Walmart said store workers would receive "extensive" training "to ensure the price-match policy is executed consistently across all stores," that hasn't happened, said Richard Hampton, an overnight customer-service manager at a Walmart Supercenter in Rowlett, Texas.

"The company policy may well be as intended in the ads, but the reality is quite different and apparently arbitrary," said Hampton, 61, who said customers have complained that stores in neighboring towns cite different price-matching rules. "As one who managed the cashiers, it was necessary for me to know the exact nature of those restrictions, and I could never get a consistent answer. Today it's this; tomorrow it's that."