In this showdown, some beer enthusiasts prefer David over Goliath. But many drinkers aren't aware of the difference between the two—and if they do, they might not care much.

Tired of watching mainstream beer sales fall while the craft beer craze soared, large international companies like MillerCoors and Anheuser-Busch InBev have hijacked the playbook of small, independent brewers. The results are faux “crafty” beers like Blue Moon and Shock Top, which appear to be created by smalltime operations, while actually being produced by the world’s largest brewers. Naturally, the authentic little guys aren’t pleased.

In 2011, total beer sales fell by 1.3% by volume in the U.S. Craft beer sales, however, rose by 13%. So-called “crafty” beers owned by mass-market brewers also fared well: Blue Moon sales increased 21% year-over-year.

While mom-and-pop brewers generally earn their reputations as laidback types—often starting businesses in their basement, with the help and advice of other brewers—they’ve taken great umbrage recently over the muddling of the craft beer market.

The Brewers Association (“A Passionate Voice for Craft Brewers”) has grown especially sick of Big Beer creeping in on its territory, and is accusing the big guys of intentionally trying to fool the public. The association consists of around 1,500 independent U.S. brewers, and it defines craft beer in specific terms. To qualify, a true craft beer must be brewed in quantities of no more than six million barrels annually, and no large international beverage company can own more than 25% of the operation. Many beers that seem like craft products don’t pass muster, according to a statement released by the Brewers Association in mid-December:

Many non-standard, non-light “crafty” beers found in the marketplace today are not labeled as products of large breweries. So when someone is drinking a Blue Moon Belgian Wheat Beer, they often believe that it’s from a craft brewer, since there is no clear indication that it’s made by SABMiller. The same goes for Shock Top, a brand that is 100 percent owned by Anheuser-Bush InBev, and several others that are owned by a multinational brewing and beverage company.

(MORE: Beer Enters the Dark Ages)

The indy brewers are accusing Big Beer of intentionally duping the public, and they’re calling for the practice to stop:

The large, multinational brewers appear to be deliberately attempting to blur the lines between their crafty, craft-like beers and true craft beers from today’s small and independent brewers. We call for transparency in brand ownership and for information to be clearly presented in a way that allows beer drinkers to make an informed choice about who brewed the beer they are drinking.

In an op-ed in the St. Louis Post-Dispatch (hometown paper of Anheuser-Busch, at least until it was purchased by a Belgian company), Brewer Association executives named names of several high-profile sell-outs—brands that were once true craft beers, but that were bought out by mass-market players:

The large brewers also have bought or own 100 percent of smaller breweries like Goose Island, Leinenkugel and Henry Weinhard. They own significant equity stakes in Red Hook, Widmer and Kona breweries. They sell these beers through their strong distribution channels, but market these faux-craft beers as if they were from independent, locally owned craft breweries.

(MORE: In San Diego, a Craft Beer Scene Emerges)

The big companies have even occasionally tried to boldly portray their products as small craft brews right in the little guys’ backyards. The Denver Post’s beer blog called attention to how a billboard pumped up Shock Top as proudly “made in Fort Collins.” This is true—Anheuser-Busch owns a brewery in Fort Collins, where it makes Shock Top, as well as Busch, Bud Light, Michelob, Natural Light, and other beers that most certainly aren’t craft beers. But the problem that the little brewers have with the billboard is that it portrays Shock Top as akin to New Belgium Brewing, which is based in Fort Collins and is known for brands like Fat Tire, which undeniably earns the craft beer label. The Shock Top logo is also a little too similar to New Belgium’s, in some observers’ minds.

Another Colorado brewer, Eric Wallace, of Left Hand Brewing, explained to the Denver Post why anyone should care about where their beer is made:

“The authenticity of craft brewing is one of the cool things about it,” Wallace said. “It’s one of the things attractive to people – the fact you can come down to the tasting room, and there are the guys who work here, it’s all made here, they can have a pint and rub shoulders and talk to them about what they’re doing. There is almost a sense of ownership in the community.”

Big beer views the situation differently. In an interview with Fortune, Graham Mackay, of SABMiller (which oversees Blue Moon, among other “crafty” beers), said that the determination of authenticity should be left to beer drinkers:

There’s a huge debate in the craft world about us, all big brewers, because we’re like the enemy. We’re the other guys. They think we’re stealing their authenticity. What we say is, “Let the consumer decide.” If we’re authentic enough for the consumer, that’s authentic enough for anyone.

(MORE: Are Twinkies a Good Investment? Scouring the eBay Track Record)

Even among the protectors of the “craft beer” label, there’s been a willingness to redefine the term from time to time. In 2010, the Brewers Association upped its limit for qualifying as a craft brewer from two million to six million barrels, so that Yuengling and Samuel Adams would still get to call themselves authentic craft beers without shame.

Regardless, the biggest beer snobs out there don’t really consider Yuengling or Sam Adams to be craft beers. Countless other drinkers couldn’t care less about whether a beer truly deserves the “craft beer” label, so long as it tastes good. In a Bloomberg News story, Jim Koch, CEO of Boston Beer (maker of Sam Adams), offered what’s probably the simplest and best explanation for why people are have been buying more Blue Moon, Sam Adams, and Fat Tire alike: