TURN ON THE TV late one night and you'll see them, those ads for gadgets that slice, dice, peel, core, do just about everything but cauterse. Yours for a low, low price if you ACT NOW and send a check or money order to a box number in some obscure location.

NBC's "Saturday Night" has spoofed these gadgets - and the ads for them - in a commercial for something called the "Bassomatic" (put one whole dead fish in a blender-like contraption and flip the switch).

While there may not be a Bassomatic in your future, each year housewares manufacturers and the retail outlets that stock their products get together for national trade shows to display their latest products and take a look at the competition. These products range from simple inexpensive objects like apple corers - which make kitchen cores a lot easier - to a $3,500 electric closet, which eliminates scrounging throught the back of your closet to find that lost shoe.

Gadgets are a lucrative business as well as something of a national passion. Last year Hammacher Schlemmer, the internationally known firm based in New York, sold well over $20 million worth of gadgets. At least 75 per cent of the firm's business is mailorder, says Charles Patteson, director of public relations.

While some gadgets seem useless, expensive and more than a little ludicrous, other are cheap, fun, useful, ingenious and well-designed.

New products introduced at the last national housewares show include a cordless electric pencil sharpener, plant moisturizer, four-quart self-buttering popcorn machine, a steel beercan tree that can display up to 300 cans, a device that renders soap bats and shampoo tubes obsolete by dispensing liquid soap, shampoo and conditioner, and oven fruit dryer, a disposable magnetic flashlight, a thermostat control that automatically cuts back the nighttime temperature and turns on heat a hour before wakeup time and a rotary toaster.

This gadget is advertised as "revolutionary . . . the first major change in toaster design in more than 20 years."

The Roly Toaster, as it's called, ejects toast onto a plate or countertop. Malfunctioning conventional toasters have been known to pop toast onto the counter or floor. Like toaster ovens, the Roly Toaster enables its user to toast open-face sandwiches and rolls. It sells for $35-$45. Toaster ovens commonly retail for $25-$40.

For those who find pushing blender buttons a bother, Waring has come out with "Softouch . . . the blendor with a brain," which has a "revoluntionary" pressure sensitive switch. The blender is being test marketed nor and is expected to be available nationally in three months for $99.95.

For those tired of boring telephone-answering machine messages there are "Hellos." A press release from Communico, the company that marked them, says "Hellos" were created by some zany recording executives in Hollywood who were . . . tired of being [WORD ILLEGIBLE] stiff by answering machine messages (and) sat down and created . . . a [WORD ILLEGIBLE] of hilarious recordings to answer their personal phones."

Available are "voice imitations" (Marlon Brando, Liberace, Richard [WORD ILLEGIBLE] "characters" based on a wide range of ethnic stereotypes," ("Olga the [WORD ILLEGIBLE] "Wong the Houseboy," "Mario the Chauffeur") and "singing imitations" (Cher, Perry Como, Johnny Mathis, Elton John.)

According to sales manager Len Castle Communico, which is based in Burlingame, Calif., has sold thousands of the $9.95 cassettes, mostly to Californians, Castle says of his customers. "They're no particular breed of cat. The cassettes appeal to all types of people.

While the Fone-A-Lert might be helpful for people with impaired hearing-who don't want to miss calls when they're home, it could also push someone who deals with busy phones at work all day over the brink.Whe hookep up to a telephone, this gadget, available for $17.95 from Hammacher Schlemmer, emits a "shrill, piercing, intermittent signal" synchronized to the ringing of the phone.

Also available form Hammacher Schlemmer and a good many otner shops is a digital counter jump rope ($10), a newspapers log roller ($14.95) and an electrically heated towel stand ($129.50).

The turnpike toll gun is great for those with short arms or a bad aim. This gadget, available by mail from The Game Room, P.O. Box 1816, Washington, D.C. 20012, shoots change into turnpike toll baskets.

The Game Room also sells Talking Refrigerator for $6.95. Each time the refrigerator door is opened this gadget says guilt-inducing things like "No wonder you're getting fat."

"Gadgets have always been a big business," says Bloomingdale's gadget manager, Scott Silverman. "It used to be that the market was limited. Now we're carrying a lot more specialized gadgets."

Specialized is right. The gadget section in Bloomingdale's White Flint store features many items designed for ethnic cooking, which local housewared buyers say is currently very big. What is less clear is how many of these items differ from more conventional, multi-purpose gadgets that weren't earmarked to perform one specific task.

In stock, for example, is a Mexican chocolate stirrer for making Mexican hot chocolate and an Indian work called a Karhai which is, Silvermans words, "less clunky" than the Chinese wok.

Bloomingdale's also carries a lucite bagel slicer, which sells for $5.50, a $4 taco fryer for those who've tired of the ordinary skillet and tongs or deep fat fryer and a $150 corkscrew that removes the cork from a wine bottle in one movement.

Bloomingdale's isn't the only store that caters to gadget-conscious Washingtons.Hecht's housewares buyers Skip Simmons says that his chain is opening "gadgeterials" in each of its stores. Joan Detwiler, housewares manager of Hecht's Landmark store, describes the response to the periodic 88-cent gadget sales as "phenomenal, the sort you never see on the first day of a dress sale."

Woodward and Lothrop housewares buyer Steve Currier says the downtown store has a number of regular customers who spend their lunch hours browsing through the gadget section. Currier explains the appeal of kitchen gadgets this way: "Quiche is no longer something people only go to a restaurant to eat. That's true of lots of foods. People seem to want to spend their extra money on these things."

Best-selling Washington gadgets include lettuce dryers, crepe and pasta makers, stainless steel vegetable steamers, graters and James Beard's salad hands, which cost $10 and are simply two wooden tongs shaped like hands that are somehow supposed to toss salad better.

Blanche Sussman is gadget buyer for the China Closet, which has long carried the sort of European kitchen gadgets that area department stores are now beginning to import. She says she stocks items like the battery-operated flour sifter for people like herself who have arthritis and find the operation of standard manual kitchen gadgets difficult.

Maybe you're wondering how people managed before the proliferation of ethnic-electric-digital-color-coordinated gadgets. So, to seems, do some children. Recently a kindergarten teacher in a affluent suburb wanted to show her students how water freezes to make ice. So she fiiled a metal ice cube tray and left it outside until the water froze. The children found the demonstration fascinating, especially since none of them knew what an ice cube tray was. They all came from homes with automatic icemakers. CAPTION: Picture, A humidifier for your greenery [WORD ILLEGIBLE]