The guest list is pure glitter - Bob Hope and his Hollywood friends; the occasion, pure gain - a projected $400,000 for the USO; the setting tonight when it all gets underway, pure status - the White House.

It's part of the 75th birthday celebration and gala fund-raiser the United Service Organization is tossing in the name of the guy who traveled 6 million miles to provide at least that many laughs for American servicemen stationed around the globe.

And it points up a little-known practice in Executive Mansion entertaining: reimbusement of the White House by groups eager for the pleasure of its company. The new wrinkle under the Carter administration is to include a White House reception in a gala fund-raiser package.

Rex Scouten, chief usher at the White House, says that while fund-raising related activities - political and non-political - were unheard of, there is nothing new or very unusual about groups picking up the tab for their White House parties.

He remembers that Lady Bird Johnson was "very sensitive," about fund-raising activities and that even on her beautification program, such events were held some place other than the White House.

J.B. West, Scouten's predecessor who retired in 1969, says of White House receptions within a benefit-gala, "There was never anything like that."

In recent years, the number of receptions has increased considerably over what West remembers from previous administrations. "Part of the reason was they didn't have a large enough entertainment budget."

Tish Baldridge, who worked with West when she was social secretary to John Kennedy, says, "In the Kennedy era, entertaining was very controlled. We didn't have big mass movements of people."

Whatever the price, if the White House agrees to hold the party, the host group will get a welcome by the president or first lady or, as in the case of the USO, both. Nothing is held in the mansion, says social secretary Gretchen Poston, unless one of the Carters is present.

For the pleasure of the Carters' company, the USO, for instance, can expect to pay between $12 and $15 a person (500 are invited tonight for a menu of champagne, wine, fruit juice, steamship round of beef, rolls, marinated mushrooms, quiche lorraine, pastries and Rosalynn Carter's cheese ring. With a more limited budget, the per-person cost of $5 buys wine and cheese.

Stripped of glamor and behind the mind-boggling aura of tuxedoed waiters, gleaming silver trays, a military band in the foyer and a presidential handshake is a strictly business operation that somebody has to pay for.

That "somebody" may be the president (i.e., the American taxpayer), an agency or department of the federal government (i.e., the American taxpayer), the Democratic - or Republican - National Committee (contributors to the party). Or it may be a private group or trade association whose eligibility and motives are considered by the president and his staff worthy of being received at the White House.

Scouten, whose staff orders party supplies, hires extra help and pays the bills when it's all over, says: "If it's an organization that has a budget and would have a reception anyway at some hotel, but asked to have it here - and the president and first lady decided to have it - sure, they would be asked to reimburse us."

In recent months, for instance, the Carters have welcomed such diverse groups as the National Panama Canal Citizens Committee, the finance committee of the Democratic National Committee, the executive council of the International Association of Machinists and Aero-space Workers, the National Conference of Mayors and the Society of American Florists and Ornamental Horticulturists.

According to the White House, the State Department paid for the Panama Canal group, the Democrats paid for its finance committee and for the machinists, the White House paid for the mayors and the florists paid for themselves.

The American Film Institute may have started the reception within a gala trend last November when its director, George Stevens Jr., approached the White House about hosting a party preceding its 10th anniversary fund-raiser. It proved to be a combination of events that ultimately reaped an estimated $350,000 in ticket sales and television proceeds.

The assemblage of film stars and motion-picture tycoons greeted by the Carters in the East Room was impressive, and the White House itself a compelling attraction to the guests.

Olivia de Havilland told of finding the invitation among her mail back home in Paris when she arrived there from a trip. "I turned around and flew back here," she said.

Two months later, following AFI's lead, Ford's Theatre celebrated its 10th anniversary with another televised gala. It, too, was preceded by a party at the White House. The net take from tickets and TV later was estimated to be around $400,000.

"For people around the country," says Alma Viator, spokeswoman for Ford's, "it was quite a thrill to get that White House invitation in the mail. I had people calling me ahead of time and asking if I thought I could get a picture of them with the president."

Aiming for equally high stakes, USO turned to Rafshoon Communications, the same people who produced Jimmy Carter's Inaugural Gala in January 1977. With James Lipton Productions, Rafshoon is producing tomorrow night's three-hour gala, the television rights of which have been bought by NEC for a May 29 telecast.

"Being associated with the Inaugural Gala was actually more beneficial in producing this show than being associated with Jimmy Carter," says McAdory Lipscomb Jr., spokesman for Rafshoon Communications, whose president, Gerald Rafshoon, will take on the $56,000-a-year job of improving Carter's image on Jul 1.

Rafshoon, however, left it to the USO to arrange social activities surrounding the gala. USO, in turn, hired two arts-related public relations consulting firms. Washington Corporative Arts, headed by Muffy Bradon, put together volunteer committees and processed invitations. Campbell, Peachey and Associates handled "front-of-the-house" details much as it did for AFI and Ford's. That included advising USO on setting up a White House reception.

"I just assumed it would be cheaper than if we hired a caterer," Carolyn Peachey says of the AFI reception.

The absence of a middleman was one advantage to having a White House link. Recognition was another factor. Guests receiving invitations to subscribe to the gala had no problem with an event's respectability.

"It's a pretty high percentage on the acceptance rate, not at all like selling a benefit," says Peachey.

Poston says a group of White House staff members assist President and Mrs. Carter in deciding which requests for White House receptions will be approved, and that each request is considered on its individual merits.

On a couple of recent occasions, signals have gotton switched and groups that did not offer to pick up the tab had the distinct impression that the White House expected to do so.

When the mayors were working out details of their January reception, "someplace in the negotiations there was a conversation instituted about who would pay for the reception," says the group's spokesman, Gene Russell."I think it was resolved that the mayors would not pay."

More recently, the Washington National Symphony notified members of its board of directors that there would be a $10 charge to attend the White House reception Mrs. Carter was giving in connection with the group's bi-annual national trustees meeting.

It took a late-night telephone call to John Henry, the symphony's director of development, by Poston, out of town on vacation, to smooth things over.

"She told me great big trade organizations couldn't use taxpayers' money for receptions at the White House but that Mrs. Carter had wanted to entertain us - a nonprofit group - all along. It was," says Henry, "a colossal misunderstanding."