Dec. 27, 2009 -- Jackie Furback, a bartender at Gatsby's Bar in New York City, said the last time she used a personal breathalyzer was at a party.
"I know two people that have them," she said. "The only time they've used them is at parties in competition for how drunk they could get."
But beyond drinking games, the devices are increasingly being used in private homes, at workplaces and by individuals who are worried about driving drunk.
Breathalyzers, originally used only by police officers, are now a booming market according to Massachusetts-based WinterGreen Research, which currently values the breathalyzer market at $215.2 million, up from $27.9 million in 2005.
"The technology has gotten cheaper," said Susan Eustis, president and CEO of WinterGreen Research. "We had major breakthroughs in the fuel-cell censors. They're much more reliable."
Less expensive breathalyzers use semiconductor censors rather than the more expensive fuel-cell censors used in most commercial-grade breathalyzers used by law enforcement, and that's where some worry about reliability. Breathalyzers are sold at major retailers including amazon.com and Target for anywhere from a few dollars to a few hundred dollars.
ABC News compared two breathalyzers with bar patrons -- one, an inexpensive $15 keychain device, the other a more high-tech model that sold for $50.
The test subject was Jeremy Turnhill, a 280-pound, 6-foot-2 male. After Turnhill drank two beers, the keychain device gave him a reading up to .08, the legal limit for driving. The more expensive model gave him a reading of .05.
Turnhill said he suspects the keychain device, which said "novelty" on the packaging, was just that, and that he thinks the more expensive model was more accurate.
"One of the most important things to consider when you're talking about accuracy is that devices are going to have low precision when they're low quality," said Charles Lee, general manager of AK Solutions, which produces various types of personal breathalyzers.
Lee suggested that consumers make sure if they are using the devices to decide whether to drive that they use Department of Transportation-approved devices, but he says that a breathalyzer test should be only one tool for making informed decisions.
"If someone buys a breathalyzer for the purpose of drinking but staying under the DUI limit, they've already made a mistake," says Lee.
When patrol officers stop drivers they suspect of being drunk, they use various field sobriety tests. It is possible that an individual can be below the .08 legal limit on a breathalyzer, but still exhibit signs of being under the influence and be arrested.
Officer Jacob Ellsworth with the California Highway Patrol uses the breathalyzer hundreds of times a year, but he says it is only one test.
"I'm comfortable enough with my job that if I don't have [the breathalyzer], I would still be able to determine whether someone is under the influence of alcohol or not," said Ellsworth.
Eustis says that between the $75 to $100 price range, "you begin to see technology that's delivering some accuracy and a level of confidence."
While most law enforcement agencies advise against using personal breathalyzers to judge whether an individual should drive, Eustis points out that the device may prove useful when trying to prove to someone that they should not drive.
"Anyone who has tried to stop someone from drinking knows it's not enough to tell them," Eustis said. "You really have to have some evidence."
Turnhill, who received the mixed results, said he envisions using such a device to test his teenage children.
"Would I use it on my own kids? Definitely I would, yeah," he said. "If they're starting to drive and I'm starting to get a feeling they're drinking and driving."
But when it comes to himself, he relies on a personal policy of never drinking and driving that is far more fool-proof than a breathalyzer.