They're usually younger Americans who drive from one winery to another to knock back drinks, with their behaviour prompting action by wineries that have started to draw up etiquette guides, ban bus tours and charge for entry.
Jane Starwood, editor of The Wine Press, says the Long Island wineries – located about 90 miles due east of New York City – have established a "card system" just like in soccer.
"If a group comes into a winery and they're really loud and rowdy, they're given yellow or red cards and warnings," she said.
In California, it's an occasional Saturday occurrence at the Tobin James winery in Paso Robles, said co-owner Lance Silver. Located some 200 miles south of San Francisco, the winery doesn't charge for its tasting as many of its competitors do.
"We know if you taste our wine, you'll probably like it and buy a bottle," he said, adding that some 70 percent of Tobin James wine sales come from the tasting room. He believes the 2,500 square foot space, the winery's focal point, is the largest tasting room in the county.
Bus tours banned
"Now 90 percent of the folks who come are just fine, but then there's always that one group," Silver said.
"They're loud and disturbing because they've been to five wineries already. And they're drunk. And they try to steal a few things because they think it's funny. They're limo lushes."
"It always seems to be a bachelorette party that is here more for the drinking than the tasting," said Miner Family Vineyards' spokeswoman Mia Beuhler.
But she had a few more tips; never pour your own tastes. You may think you're helping a busy pourer, but you're really only getting them in trouble and making yourself unwelcome.