Charles Dickens would take one look at Don Perkinson and yell for the fraud squad.

Here is a young man who bills himself as The Chimney Sweep. But he seldom sets foot on a roof. He uses an electric vacuum cleaner as often as a brush.He drives to and from jobs in a snappy, pearl-gray truck, and he hands out business cards the color of tomatoes.

But rest easy, Mr. Dickens. It's only modernization come acreeping.

Don Perkinson, The Chimney Sweep, wears the top hat and morning coat your sweeps helped make famous. And he gets plenty dirty. But the main thing is that, as he fights his way through Washington's soot, Perkinson is making a better living as a sweep than any Dickensian wretch ever did.

It has been less than a year since Perkinson was an unhappy ad salesman for the Yellow Pages. On the advice of a customer who cleaned fireplaces, Perkinson quit his job, invested $300 and one week of training and declared himself a chimney man. "My friends said I was nuts," Perkinsonn says, "but here I am."

And he is well on his way to becoming established. Although Perkinson is but one of 26 Washington-area sweeps who advertise, he is one of the few whose livelihood is nothing but sweeping, and one of the few who works alone. He averages about 12 calls a week at $40 for the first chimney, $25 for each additional, pretty much standard rates in the area.

But the money is secondary to the stir Perkinson can cause. A tall, blond 29-year-old with a flowing, reddish beard would cause one, anyway. Dress him up as a vagabond Abe Lincoln, however, and the kids come running. "Yean, they're always asking me if I know Mary Poppins, or if I'm a magician," says Perkinson, a Kentuckian who came to Washington as a teen-ager to visit a brother and never left. "The older ones are always on me, too-'Hey, man, are you a weirdo?'-that kind of thing."

Once on the job, Perkinson has to put up with people who want his photograph, pets who insist on getting in the way and robins who have firmly implanted nests in hard-to-reach places. Meanwhile, there is the old tale that touching a chimney sweep brings luck. "So I get touched. A lot," Perkinson says.

His most bizarre customer, Perkinson says, was a householder who got a glimpse of The Chimney Sweep walking up the driveway in his hat and coat. "He laughed at me for the next hour solid."

And the sweeping career itself got off to a rocky start. "I remember my first job very well. I lost a brush up there."

But, by now, the moves are routine. Using a soot bin, a motor and vacuum pipe that hook onto it, a tool kit, various buckets and wire brushes, Perkinson can do most chimneys in an hour.

He does them from the inside of the house up, rather than the reverse, because it is easier to reach accumulated crud. Perkinson snaps together eight sections of pipe to form a pole about 24 feet long. To the business end of the pole, he attaches a wire brush. Then he works the contraption up and down the chimney, like a man milking a giant cow.

"The only thing you can't mind in this job is getting dirty," Perkinson says. "But it's good, honest dirt."

Actually, it's a combination of garden-variety soot and a sticky substance called creosote. Soot, of course, is produced by the burning process. Creosote is formed from the chemical reaction of acide in smoke amd moisture in wood. Burning green or soft wood, or not burning logs fully, will produce creosote.

Most of the time, creosote simply sits along the inside of a chimney. But creosote is flammable, and a healthy layer of it can make a chimney an inferno.

If a creosote chip were to fly up the chimney and land on the roof, a fire could easily start. According to figures from the Metropolitan Washington Council of Governments, more than 3,000 home fires in the Washington area were believed to have started that way in 1977.

Thus, Don Perkinson's business is really prevention. He is like a dental hygienist who scrapes away at teeth. No one really notices the cure, but once it is performed, no one notices the disease, either.

Not that Perkinson doesn't have gripes. He must kneel all day on rock-hard hearths. He must wear a mask so his lungs don't get sooty. He must figure on 45 minutes in the shower after each day's work if he wants his girl friend within ten yards of him.

Worst of all are the hands. Untold tons of industrial soap have gone into their pores, but a gray film remains nevertheless. And to smell Perkinson's top hat or coat would be to ruin a week's appetite.

Meanwhile, the nature of his business is somewhat insecure. Even though protecting a home's resale value in Washington is next to godliness, Perkinson well knows that most homeowners think of having a chimney swept as a frill.

So, while his business is booming this fall, as people prepare for the fireplace season, it might bust during the spring. "I'm sure the lack of security is the reason more people aren't sweeping, even though it only cost me $2,500 to get my equipment and get started," Perkinson says.

"But I feel like a king," said The Chimney Sweep, as he poked away at a flue in Springfield one recent morning. "I felt great that day I put my suits and ties away. I kinda likemy boss right now. He's easy to work for."