"This is not supposed to be about getting drunk," said Kelliher, an architect of Responsible Partners, who transported 21,000 visitors through Temecula wineries last year. "There's a big difference between pleasantly intoxicated and falling-down drunk, and if you don't know what it is then you shouldn't be in the business."
Mark Pondoff, whose Orange County-based Party Lounge buses feature mega-sound systems, cocktail waitresses and stripper poles, said he's thinking about directing his guests away from the Temecula Valley, where he does only a small fraction of his business.
"People want to go where they feel wanted," said Pondoff, whose nom de bus is Capt. Marky Mark. "Why should I bring them customers if they treat us like dirtbags?"
Some wineries say they'd rather lose the business. Rowdy limo groups "have a history of not being really great buyers," said Root, the tasting-room expert. "My hunch is they've blown all their money on the limo."
Wine enthusiasts often make their treks on weekdays to avoid the weekend roisterers.
"We have serious aficionados who come here to taste, to meet with the winemakers, to see what's new and exciting coming out of the Santa Ynez Valley," said John Tomasso, an oenophile who lives in Buellton.
"But for others -- it might be a limo full of women from a bachelorette party -- it's kind of a Disneyland day, and they want to consume as much as they can, as quickly as they can."
When Tomasso spots a limo at a tasting room, he tends to drive on. "You hope your luck is better at the next one," he said.
To be sure, most buses and limos carry the mildly buzzed rather than the majorly blitzed. And most tasting rooms aren't Party Central, especially off-season or on a weekday.
In an hour at the Fess Parker winery in Los Olivos one recent Saturday , there was pleasant chitchat and spirited conversation but nothing approaching even a heated argument about the merits of screw-tops.
At a winery a few miles away, though, a Bakersfield man who had just turned 40 was enthusing -- loudly -- about the limo he had rented for the occasion.
"If I didn't get a limo, I'd be DUI from Day One," he said. "I like to drink, I like to party, and no one can tell me I can't."
Winery managers and law enforcement officers say that's not exactly true.
The local sheriff's office gives classes to winery employees on, among other things, how to cut off insistent drunks. It's a skill that comes in particularly handy on busy summer Saturdays, when traffic can clog the area's narrow, winding roads and high-volume high jinks can boom through the wineries.
Safety is a concern as well. Last week, the California Highway Patrol announced a $658,000 effort to curb drunk driving around the wineries in Santa Barbara County.
Jim Fiolek, director of the Santa Barbara County Vintners Assn., said his region continues to feel the effects of "Sideways," the 2004 movie about two buddies and their drunken week at the local wineries.
Even four years later, crowds want to have the rowdy good times portrayed in the film. "At least three times, we've heard of people drinking the dump bucket just to get pictures of themselves doing it," Fiolek said.
Still, "Sideways" also has brought newcomers willing to pay for good wine.
"Look what it's done for Pinot Noir," he said. "Try to find a cheap one anywhere."