What is cable TV the greatest thing since? Maybe Glad Bags, or NutraSweet, or the Slinky. But it is not the greatest thing since television. After having it in your home for a while, the thrill wears off with a thud, like it does with a personal computer. You begin to resent it, to hate it; the compact disc player and VCR seem infinitely more benign technological intruders.

Considering the complications and postponements that have plagued the District's herky-jerky cable plans, and despite the fact that District Cablevision Inc. yesterday delivered a schedule to the D.C. City Council for wiring the city, the possibility still remains that the District won't fully be wired until cable is obsolete and pint-sized satellite dishes are all the rage. That may not be a tragedy for the citizens of the capital. The only prayers that cable seems to answer are businessmen's.

At the moment, cable TV systems and networks nationwide are cooperating in a public relations campaign to discourage people from "stealing" cable TV programming. It seems some enterprising souls manage to patch into their local cable systems without paying; others get premium services like Home Box Office and Showtime for free through one form of technical mischief or another.

If the cable industry spent as much time upgrading its services and improving its product as it does scrambling signals and snuffing out pirates, cable TV might not be quite the mega-letdown that it is. When one compares the reality of Cable 1985 with the sky-pie promises of yesteryear, one sees a hungry fat frog that started out as a public-spirited prince. While never one to encourage law breaking, I cannot for the life of me imagine a more defensible crime than putting one over on the pikers who run cable TV. Putting one over on them should come under the heading of justifiable revenge.

As infuriating as cable TV can be -- whether it's poor service from one's local cable system or the agony of endlessly repeated movies on pay channels -- it may soon be getting worse. Two decisions this summer that affect cable TV will enable it to become more expensive and less responsive. The abiding goal of the cable industry may be to deliver less while charging more; that wouldn't make it unique in the annals of business.

In July, the Federal Communications Commission (FCC), which bravely champions the rights of media empires to grow larger, decided to curtail sharply the control local governments have over the rates cable TV systems charge their subscribers. All over America, basic cable rates are leaping up. If the ruling survives challenges in court and Congress, cable system owners will be free to raise rates willy-nilly without community approval.

What a bungling deregulatory commission won't do, a wacky judge might. In one of the least appealing judicial pronouncements since a federal judge destroyed the phone company, a three-judge panel of the U.S. Court of Appeals decided in July to strike down the so-called "must-carry" rules affecting cablecasters. The rules required cable systems to offer their subscribers all available TV stations in their service area.

This sometimes did lead to duplication of program choices (if, for instance, there were two ABC affiliates or two public TV stations on the same cable system), but it also helped keep the system and the service locally accountable. The FCC subsequently decided it would not appeal the court's decision. Under Chairman Mark S. Fowler, the commission acknowledges as legitimate only the pressures of "the marketplace," not, as the commission was founded to protect, "the public interest, convenience and necessity." Wait a minute -- does the word "marketplace" appear in the Constitution? Did our forefathers and foremothers fight that brave little war against England two centuries ago so they could establish nothing loftier or nobler than a darn marketplace?

If appeals now being pursued by the National Association of Broadcasters and others fail, must-carry will be history by Sept. 13, which means local cable operators can start dropping minority-interest stations that don't bring them revenue in favor of something that does, like premium channels viewers must pay to receive or one of Ted Turner's sundry slapdash enterprises. Must-carry was a burden to small cable systems of 12-channel capacity, but those systems need to be retooled anyway. For a system of 40 channels or more, must-carry was hardly a hindrance.

Cable TV systems are virtual monopolies, and cable TV is almost a common carrier. It's like plumbing, only it delivers information instead of water, and it has the virtue over regular television of providing a vast multiplicity of voices. You can try to do without it, once it is installed in your city, but that can get a little lonely. This summer's decisions on cable raise the possibility of cable operators pricing cable TV, more of a necessity by now than a luxury, beyond the means of lower income viewers. The whole idea of "narrowcasting," which meant that cable TV would be able to accommodate and cater to special tastes and interests ignored by mass-market television, seems to have died in the operator's rush to revenues.

Certainly there are responsible and upstanding cable operators out there in the land. But the barrel appears to have more bad apples than it should. Even at a basic technical competency level, cable fails; the wired viewer discovers some, or all, cable channels may vanish completely at any given moment. If, say, a tree falls in the forest, no one may hear it, but it will probably knock out the cable TV. Such a delicate, sensitive technology! Rain or shine, my cable system is unable to deliver routinely to me an acceptable signal on such exotic channels as 4, 7 and 9; if I stood on my roof, I could see these local stations' transmitting towers. HBO, however, comes in pretty good from outer space.

Some cable operators are specialists in one-way communication. If you try to reach them to complain about miserable service, you can get a busy signal for eight hours straight; but if you are a few days late with your monthly payment, you can practically expect death threats, smear campaigns and a burning antenna on your front lawn. Cable TV is an act on which a great deal of cleaning up needs to be done. Until that occurs, it's hard not to regard cable TV pirates as the guerrilla fighters of the video revolution.