Some of Fairfax County's first families with cable television say that even 126 channels don't guarantee video utopia.

Residents of Tremont Gardens, a subdivision of 136 homes between Lee Highway and Rte. 50 about three-quarters of a mile inside the Beltway, say they are pleased with the quality of Media General Cable's system itself, but some lodge stern complaints about what they describe as pushy salesmen who offered hazy--and some say deceptive--information about rates and services.

About 25 households in the Tremont Gardens area have elected to begin cable service as part of Media General's debut of its system in Fairfax County. The company received its franchise from the county last summer after a long and still-contested battle with Fairfax Telecommunications Co.

Richard and Mary Jansen of Fairmont Street, who are both retired, said the Media General salesman who visited them last week quoted $21.11 a month as the cost of the least expensive service available. They since have learned, they said, that $3.07 is more like it.

Emily Rome, also of Fairmont Street, said the salesman who came to her door at dinnertime "was worse than the encylopedia salesmen. 'I don't like television,' I told him. 'Why would I want that?' I had to tell him five or six times to go away. Finally I literally closed the door in his face."

Kenneth Hurd complained to Albert Crider, president of the area's civic association, that he was sold the pay channel Galavision ($7.95 a month), which turned out to feature all-Spanish programming. He said he doesn't speak a word of Spanish.

Media General says it's watching the situation closely. "We knew there were going to be problems," said Lorraine Foulds, a company spokesman. "This is a test. We're learning together. We want to learn what the problems are." She acknowledged that some--perhaps only one--of the firm's eight salesmen are "over-energetic." She added that the sales force is "going to have to realize that not everyone is as excited about the service as they are."

Media General, a representative from the Fairfax County Office of Consumer Affairs and about 30 residents met Monday night to try to iron out the situation.

"To have 30 people show up, that says something," Crider said. "Usually if we have eight or 10 people at a meeting, we're lucky."

Gail Eskew, representative of the consumer agency, said, "This is the first effort of Media General, and there are problems. But Media General seems very concerned about resolving them. Their reputation in the county is on the line."

"It wasn't what the salesman said. It was what he didn't say. He left a pretty sad taste in the mouths of a lot of people," Richard Jansen said.

For instance, some residents said, the salesmen tried and often did sell them a weekly guide to programming without telling them that a monthly guide comes free upon installation.

Area residents say they first received documentation of the comparative rates on Sunday when Crider, of the civic association, copied and distributed a copy of the rate schedule he obtained from the office of County Supervisor James M. Scott.

"The advantage, if you will, of these people being guinea pigs, is that they can call and get their contracts changed," said Foulds. After the trial period is over, she said, and Media General works the bugs out of the system, the company won't be as flexible.

In addition, those buying cable service now will receive credit on their bills for "however long it takes to straighten things out," Foulds said.

Foulds said Media General will extend its service area eastward from Tremont Gardens to the subdivisions of Tyler Park, Fenwick Park, Denvonshire Gardens, Jefferson Village, Woodley North, Hillwood and Idylwood in early September.

By mid-September, service will begin in parts of the McLean area, the Parliament Village region of the Mason district and in the Kings Park area of Annandale.