From an office high above a 67-acre expanse of mud and steel billed as the biggest extravaganza ever to hit the South, a California public relations man peers down at dump trucks hauling dirt 38 days before opening day, and pops a videotape of the event's starring pitchman into the Betamax.

President Reagan appears on the screen, high above a tent pavilion nicknamed "Dolly Parton's brassiere," and plugs the 1982 world's fair--technically Energy Expo '82--whose rides, restaurants and exhibits from 23 countries are expected to lure 11 million visitors with $120 million to spend, generate 20,000 new jobs, 12,000 of which would be permanent, and create a new self-respect for this town in the Great Smoky foothills.

The impending gold rush also has spawned an ugly epidemic of greed, including mass evictions of tenants--many of them elderly, with no place else to go--by landlords itching to rent to fairgoers at inflated prices. Some have jacked up rents astronomically so tenants are forced to move.

After a media maelstrom, the city council passed an anti-eviction statute that denies zoning variances for nightly rentals to landlords who evict tenants to capitalize on the fair. But some tenant groups dismiss it as a toothless ordinance. Others say it also is illegal because the Tennessee Constitution allows landlords to charge whatever they want.

One landlord told reporters it would be "fun" to evict a few tenants to test the law. Others are attempting to get around it through sudden condominium conversions, giving tenants 60 days to buy apartments or get out.

College students are hard-hit. One student said his roommate was forced to leave school because he couldn't find a new place to live.

Trolan Needham, 63, is among an estimated 1,500 residents given notice by landlords salivating over the possibility of $100-a-night room rates for seedy apartments over the fair's six-month run.

"If they send me out, God knows where I'll stay," says Needham, a disabled ex-Marine who has until next Wednesday to vacate his $95-a-month apartment. A victim of arthritis, he lies flat on his back, an emaciated old man living alone, with a wheelchair, American flag and boxful of medicines beside his bed. He survives on visits from friends and a monthly $275 Social Security check.

"I just can't pay no more rent," he says, jabbing the TV off with a cane. "Can't rob a bank to please 'em."

Around the corner, developer Cynthia Payne steps over a stack of lumber in the old downtown hotel she just bought to renovate and rent out to fair visitors. She gave notice to seven residents who are on month-to-month leases. "We've got a penthouse with an outside jacuzzi for $165 a night that overlooks the mountains and the Chinese pavillion," she beams, elegant in a white designer suit, gold hoop earrings agleam. "We're very excited about the fair."

Indeed, the 1982 world's fair--seeded by federal largess, promoted by two presidents and plagued by controversy from the start--is different things to different people. The landscape of unfolding exotica that opens May 1 was hatched as a scheme to redevelop a blighted downtown, but got rolling only after President Carter shook Washington's money tree.

After a personal appeal from millionaire Tennessee banker Jake Butcher, Carter prodded the Department of Housing and Urban Development--over Secretary Patricia Harris' objections that Knoxville sat at the bottom of HUD's list of needy cities--to release a $13.8 million federal grant to get the project moving.

Butcher, a heavy Carter campaign contributor, was its chief booster. His United American Bank (UAB) had loaned Carter's first budget director, Bert Lance, $515,000 to buy controlling interest in the National Bank of Georgia. Lance took him to Carter, and recently jetted to Cairo to sign up Egypt as a fair exhibitor. A few artifacts from the legendary King Tut collection are being dispatched.

In the short span of seven years, Butcher and his brother, Cecil, borrowed millions to build a highly leveraged empire of 14 banks whose gleaming $28 million UAB headquarters here overlooks the site of Energy Expo '82, once a weed-infested hobo jungle. His bank property is expected to soar in value, and a host of friends and associates stands to profit from ventures associated with the fair, critics say.

Some fear that paying the the enormous debt could burden the city for years. "That's why we've got to have a good fair," says council member Bernice O'Connor. "We've got to start paying off the bonds in 1984."

But locals are starting to get behind the fair. Even critics cheer the $225 million in accelerated federal highway improvements that untangled a three-interstate bottleneck nicknamned "malfunction junction," along with $45 million in projected new tax revenues.

And to keep enthusiasm high, public relations men like Marc Grossman are pulling Ronald Reagan from an arsenal of hype to reassure visiting VIPs.

"People in Tennessee, across America and around the world are working very hard to make the fair a success," said the president, on a tape designed to hustle corporations and foreign countries for exhibits. "I have given them my full support and I hope you will as well."

"We've exploited it to the utmost," says Grossman, 26, vice president of communications for the Knoxville International Energy Exposition (KIEE), the nonprofit corporation putting on the fair. "I've shown it hundreds of times."

The tape rolls forward. Here comes Secretary of State Alexander M. Haig Jr., plugging the fair. He also courted ambassadors at a glittery State Department reception.

Twenty-three countries have signed up, more than participated in Seattle or Spokane when those cities put on similar extravaganzas. The Soviet Union dropped out after the United States imposed sanctions for its invasion of Afghanistan, but China is coming with 40 tons of Great Wall, dozens of antique artifacts and a genuine mandarin chef. Egypt is serving up a few relics from the acclaimed King Tut exhibit; Peru will trot out dazzling gold jewelry.

"You've got to do these things," said Grossman. "Not that we don't have anything of substance, but we needed all the help possible. You could never pull off an event like this without influential friends. Happily, we've got a lot of influential friends."

He ogles the Sunsphere, a gleaming $5 million gold dome atop a 266-foot steel tower whose elevators will zoom visitors into an observation platform inside what appears to be a giant gold golf ball. Nearby is the futuristic U.S. pavilion, $21 million worth of concrete and glass funded by Congress.

Consumers already have snapped up 105,000 season tickets at an average price of $55, and officials are confident the fair will draw heavily from some 52 million people within a 400-mile radius of Knoxville. Marketing director Bill Francisco also sees moderating gas prices as a boon.

But he's counting on Knoxville area residents like Jerry Basler, a $12-an-hour ironworker, to make up the bulk of the fairgoers with repeat visits. Basler leaned on a railing, stared out at the muddy panorama with his wife, Becky, and niece, Shasta. "We're going to come at least five times," he said. "I've got to try all the food."

"Of course, it's a gigantic roll of the dice," says Francisco. "People ask, 'A world's fair in Knoxville, Tennessee? You've got to be kidding.' But from the mail, the phone calls and the ticket sales, it looks like our biggest problem is going to be dealing with success. What scares me most is that when we open, we've got to open with the best possible show."

"It's going to be bananaland in Knoxville," predicts lawyer Boone Dougherty.