* Elizabeth Brinton has her critics, to be sure. There were people who griped and groaned, who said the Falls Church ninth grader broke the rules in January when she sold Girl Scout cookies to President Reagan.

But almost three months later, Brinton, who holds the unofficial world's record for selling the most scout cookies ever, seems to be vindicated.

And she is well on her way to breaking the record she set last year when she sold 11,200 boxes of cookies in a single season.

Some girl scouts and their parents, mostly the latter, made indignant calls to the scouting organization and to the news media when Brinton sold the president seven boxes of cookies at a White House ceremony in January despite the fact that cookie sales were officially embargoed until the day after the ceremony.

But the complaints backfired. After her critics were quoted in The Washington Post, Brinton, 14, received a rush of sympathy orders from people angry about the comments, which many perceived as catty and nitpicking.

The story was picked up by newspapers nationwide, and Brinton has received dozens of letters from around the country, some of them addressed only to "Cookie Queen, Falls Church."

Also since the White House ceremony, many top government officials have taken a cue from the commander-in-chief.

Among the new names on Brinton's list of celebrity customers: Vice President Bush, Treasury Secretary James A. Baker III, Energy Secretary Donald P. Hodel, Education Secretary William J. Bennett and Supreme Court Justices Sandra Day O'Connor, Harry A. Blackmun and William H. Rehnquist.

So far this season Brinton has sold about 8,000 boxes, she said, most of them through using her proven tactic of peddling to passers-by at the Crystal City Metrorail station in Arlington and the Connecticut Connection shopping center in Northwest Washington.

At that rate, she seems to be a shoo-in to break last year's record. A strong showing this year, which Brinton says will be her last for record breaking, would bring her career sales to a staggering total of 50,000 boxes.

Much of her success, Brinton frankly admits, she owes to a single human weakness: guilt.

"I look people in the eye," she said, "and they see me out there trying to sell cookies, and they think, 'How can I pass her by?' "