HAVING THE blues isn't necessarily bad. But some people need convincing.

Susan, for instance, scrunched up her nose like a little kid being forced to eat spinach. "Yech. What is it? Rattle-snake," she asked.

Her revulsion to food that had never before passed her lips was soon abated by an aroma sending a message to her brain. "This smells great," said her nose. The brain agreed.

She broke off a small piece of meat, put it in her mouth and said, "Oh! Hey, that's marvelous. What is it?"

Unlike Susan, Bob was a pushover. The second the tinfoil was peeled back, his nose quivered like a rabbit in a carrot patch. He took a bite, smacked his lips a few times and raised his eyebrows up and down before saying, "Good. Really good. Um. That's terrific. Um. Now that's just fine. Um."

What convinced Susan and delighted Bob was smoked bluefish, fresh from the Chesapeake Bay.

From the competitive points of view, the bluefish is a savory struggler known for its ravenous appetite and great strength. From the culinary point of view, it is know to have fine taste.

Fried, it can be oily if the dark colored blood vein is not fileted away. Broiled, it is less unctuous. But smoked, it is a sumptuous dish that will please all but the most ardent fishhater.

Properly smoked fish is a delicacy that is expensive at a deli and rarely found in the home refrigerator. But its piquant flavor can easily be roused from a backyard barbecue.

The main ingredient, of course, is the fish. Anglers and adventurers will have no problem catching blues in the bay this year. Charter boats dock every day along the bay shoreline and anglers use wheelbarrows to haul their catch to the cleaning stands. Home cooks will find the seafood section of grocery stores well supplied with fresh, cleaned filets of bluefish.

A local woods can provide a couple of branches of hickory, maple or apple wood, some of the hardwoods suitable for smoking. (Softer woods, such as pine, yield a strong resin that fouls the fish.) Take a hatchet and chop off small chips of wood, preferably hickory, or, if your neighborhood lacks timber, buy a bag of hickory chips. Two other items are necessary, charcoal briquettes and a grill with a lid.

Place the coals on one side of the grill only.

Meanwhile, lightly salt and pepper the bluefish filets. Then cover the filet with a strip of bacon.

Or try another preparation recipe recommended by Mike Paparella, a University of Maryland seafood technologist. "Make a marinade out of a gallon of water, a cup of salt, some brown sugar, celery salt and onion flakes. Soak the filets for about a half hour." Paparella says the solution induces a carmeling affect upon the fish that enhances the smoking process.

Brining also helps remove moistrue from the meat, firms the flesh and adds flavor.

When the filets are prepared, use a spray bottle filled with water to lightly moisten two handfuls of hickory chips. Then place the chips over the hot coals. Have one portion of the grill lightly oiled, the ares not directly over the heat. Lay the bluefish filets on this portion of the grill and close the lid. The surface temperature of the grill should not go higher than 200 to 250 degrees.

There is no need to turn the filets over. Just keep the lid closed and use the spray to control any searing flames that may spring up.

An hour and a half to two hours later, a platter full of hickory smoked bluefish will be ready to be eaten warm, or the fish may be cooled, wrapped and chilled in the refrigerator until it is needed.