Prince William County officials, troubled by allegations of questionable cable television deals in neighboring localities, have taken what they saw as the only logical way out: adopting a hands-off policy on the whole subject.

In an action many see as almost unprecedented, supervisors in the area's most rapidly developing county have decided they won't attempt to regulate or even tax the revenues of the lucrative cable television industry.

The board's decision, which could stand for three years or longer, effectively gives a strong economic advantage to two cable firms currently operating in some of the county's most densely populated areas without an approved franchise. One of the firms, Cable Television Inc., is owned by influential developer Cecil D. Hylton, who built Dale City.

Dale City area Supervisor James McCoart, an Independent, said the board's 4-to-3 decision to avoid cable regulation represents a victory for consumers. He said it will allow private enterprise to continue providing cable television service at the lowest possible rate.

"It's purely an economic decision," said McCoart. "Once you get the government regulating something, it's the consumers who pay for the regulation."

But national cable experts yesterday said the decision could work to Prince William's detriment. Without local regulation, they say, cable companies will be likely to restrict their services to the most-densely populated and wealthy areas of the county -- a practice known in the industry as "cream-skimming."

"I think the county's being very foolish for doing it," said Howard J. Gan, vice president of the Cable Television Information Center, a national nonprofit organization based in Washington that advises localities on cable franchising questions . . . " They're avoiding making a hard decision, but the public may be badly served by their decision not to make a decision."

Gan said the free-market approach endorsed by the Prince William Board gives cable companies no incentive to offer the optional services that do not produce profits but are much in demand in localities around the country: educational shows, public access channels and programming of purely local interest.

In neighboring Fairfax County and Leesburg, recent discussions of cable television have been clouded by allegations of influence-peddling. The Justice Department is embarking on a preliminary investigation of alleged antitrust violations in Leesburg, while Fairfax has slowed its franchising process to give officials more time to study the issues there.

Officials of the more than half-dozen companies interested in winning wiring rights to Prince William's 43,911 households yesterday expressed no surprise at the board's decision. They said the presence of Cable Television Inc., which serves 6,700 homes in the unincorporated Dale City area, and Triangle Cable Television Inc., which operates around the Quantico Marine Base, will discourage other companies from entering the county without a franchise.

"If I were going in, it would be very tough to compete if there were already two systems that were built and ready to run," said John Lubetkin, vice president of Matrix Enterprises Inc. a Tennessee-based firm which was interested in Prince William.

Cable Television Inc. which has been operating in Dale City since the development was built 15 years ago, yesterday announced plans to expand its service area into the eastern part of the county around Woodbridge.

That system provides its subscribers with about 16 TV channels at a cost of $15.45 a month for basic service and first-run movies. Without cable television, most Prince William County residents can receive four commercial television channels.

County Supervisor Joseph D. Reading yesterday said he was relieved he would no longer have to cope with the swarms of cable lobbyists that he said were like "termites crawling out of the woodwork."

Still, Reading said he would be watching Farifax County's deliberations on cable television with interest. "Maybe I can learn by their mistakes instead of creating my own," he said.