So he hires "mystery shoppers," contract workers who are paid to evaluate businesses while posing as regular shoppers, to come in every so often to assess the integrity of his staff, quality of customer service, food and cleanliness at his restaurants.

The service costs between $85 and $100 per visit, but he said the result — a detailed report of what works and what doesn't — is well worth it.

"The mystery shopper always gives us a third-party point of view, an objective point of view," he said. "From being seated to being waited on, what they see and notice, what they like or didn't like — we need (to know) that to grow. ... Any kind of feedback you get is invaluable."

The importance of customer satisfaction has helped launch mystery shopping into an estimated $1.5 billion industry that employs more than 1 million shoppers in the United States and 250,000 in other countries, according to the Mystery Shopping Providers Association, the largest professional trade association.

In Hawai'i, only a few companies offer the service, employing more than 100 part-time mystery shoppers who evaluate dozens of companies in industries ranging from hotels to nightclubs to golf courses.

Expectations high

About 80 percent of companies who use mystery shoppers are retailers and restaurants.

With more competition for consumer dollars, and higher expectations from customers, many businesses have started to critically examine their customer service practices, finding ways to improve employee interaction with customers in an attempt to set themselves apart from their competitors.

"People's expectations are so much higher now," Muraoka said. "They want more, they demand more. But how can we offer more? That's the key for us. ... You can offer five-star service in a diner with simple things like greeting guests, pulling out their chairs, opening doors for them. There are little things you can do."

ABC Stores has been using mystery shoppers to evaluate its customer service for 25 years. All 66 stores, including three in Las Vegas, have been assessed by these undercover shoppers.

"The shopper sees what the customer will see, goes through what the customer will go through," said Ken Ishimine, operations manager. "When we get the feedback, we focus on those areas in which we are failing, whether that may require us to change policies or procedures or put more emphasis in trying to get certain things accomplished. This is what we'll do."

Several decades ago few companies used mystery shoppers to assess customer service. Now, corporations as large as McDonald's to small mom-and-pop retailers are using the service to help them improve employee-customer interaction and, often, to check on internal theft and employee substance abuse.

"Drug problems (at work) and internal theft are on the rise, and that's where we can come into play," said Michelle Chun, mystery shopping division manager at Safeguard Services, a full-service security company. "When you're dealing with money, it's very easy to steal."

Eyes for managers

Safeguard Services trains its dozen mystery shoppers to notice cash mishandling and suspicious register activity. These shoppers then note any dubious transactions in the report given to the company.

"We're the eyes for the managers," Chun said. "They can't be there all the time."

And finding ways to improve customer service also can prevent another kind of theft — shoplifting.

"If you have good customer service and your employees are approaching customers, they're less likely to grab something," said Carol Pregill, president of Retail Merchants of Hawai'i. "It's a real preventative measure against shoplifting."

Service checklist

Muraoka hasn't had major problems with theft, although that is a concern for him. He hires mystery shoppers from Safeguard more for evaluating customer service, which is vital to any service-based business like restaurants.

He tailors the checklist for the mystery shoppers to fit his needs as a restaurant owner. Were customers greeted and thanked? Were they asked to come again? Were the dining area and restrooms clean? How was the quality of the food?

One or two mystery shoppers will dine at the restaurant, observe the staff and submit a detailed report to the restaurant. For restaurants, the visit takes around an hour. For retailers, however, visits can be as short as 10 minutes.

Some companies use these evaluations as an opportunity to reward stellar employees who provided good customer service. ABC Stores, for example, gives its employees $50 cash incentives to get positive marks.

"The program has to be sold to your employees," Ishimine said. "We tell them that these shoppers are coming into the store to help us improve our business, show us where we are failing so that we can better improve our service. Eventually, this will help us improve our sales and profits and that, in turn, will benefit them, too."

The more-than-200 employees at Big City Diner know that these evaluations are really a way for them to improve as workers. And for the most part, they're understanding.

"Most people are receptive to growing," Muraoka said. "This has helped us grow and learn. We want feedback. We want people to tell us what we're doing. We're always ... striving to improve. ... You have to pay for it, but it's the cost of running a business."