BELFAST, Maine — A few years ago, a hand-held device that could direct drivers from their dooryards to an address on the other side of the state elicited wonder. Today, when that technology fails to provide spot-on directions, users are frustrated.

But if consumers get annoyed when the GPS on their smartphone fails to lead them to their destination, imagine what business owners feel when one of the many Web mapping services leads a potential customer to the wrong location.

As many as 20 percent of business listings on Web-based map sites and services are inaccurate, says Jim LeClair, who owns and operates with his wife, Patti, the Maine Coast Welcome Center, a for-profit business on Route 1 east of downtown Belfast. As LeClair discovered the depth of the problems with what is known as data mapping, he has built a side business devoted to fixing those problems.

“We’re a regulated data mapper with Google,” he said.

Increasingly, smartphone users rely on mapping technology to find a gas station, bank, restaurant, hotel, auto repair shop or specialty store as they travel. With tourism as Maine’s largest economic sector, the consequences of being listed in the wrong place are serious, LeClair said.

One of several examples he gives is Kebo Valley Golf Club in Bar Harbor. Often, LeClair said, the club would receive phone calls from people whose directions — obtained through MapQuest, Yelp, Trip Advisor, Google and a half-dozen other sites — sent them to the wrong part of Mount Desert Island. Some maps put the golf course a mile away from its actual location.

Adding insult to injury, the poor cellphone service on the island often would cut the calls short, leaving golfers believing Kebo Valley didn’t want their business, LeClair said.

Less dramatic examples, but with potential to hurt a business’s bottom line, are restaurants that are shown around the corner from their actual street location. And just as often, a business description is inaccurate. A business specializing in gourmet olive oil with stores in Rockland and Bar Harbor was listed under oil manufacturing and edible fats — hardly enticing to customers.

The mistakes occur when “data bots” — automated data gathering programs — either make incorrect assumptions about a business location, or as they search the Web and obtain information, appropriate the wrong data.

The fix, LeClair explained, involves going to the several sites that provide mapping and “claiming” the business location. LeClair’s Data Mapping Services makes the entries, and the Web bots take the next step, absorbing the new information. Some popular mapping sites will validate the new information through automated telephone calls and others will use a very old-fashioned method — postcards.

LeClair became interested in data mapping when he got his first smartphone a year ago and discovered address anomalies.

“So I started checking into how all this stuff got listed,” he said.

His primary business, the Maine Coast Welcome Center, directs Maine visitors to lodging, restaurants, services and other businesses. Often, LeClair said, people returning south after visits to Bar Harbor stop in to report that their smartphones or GPS devices failed to locate the destination he recommended.

An example of a client whose corrected data mapping paid off, LeClair said, is BJ’s Automotive Diagnostic Center, a Belfast repair shop. A traveler not familiar with the area broke down in the Hannaford grocery store parking lot. A check of his smartphone led him to BJ’s Automotive, including a map, directions and phone number.

LeClair charges $500 to correctly list a business’ data, a fee he says pays off many times over in sales that otherwise may have been lost. In two years, he has built a client base of nearly 100 businesses and organizations.

LeClair can be contacted at 415-5646 or at