Behind many of Washington's free-spirited, wheeled messengers is a network of well-organized and surprisingly profitable companies, according to Robert Hess, a founder of the new Washington Metropolitan Courier Association.

"There are more than 150 courier services in Washington, and some of these companies have revenues in excess of $5 million," said Hess, who is president of Datrex Corp., a computer firm in Washington that automates courier companies.

The courier business is changing from small mom-and-pop companies into a professional, automated industry that is growing quickly, he said. In Washington alone, the industry employs approximately 4,000 people, according to Hess, who said that these firms make about $130 million a year.

The association's founding members will rely on strength in numbers to draw attention to the industry's concerns, which they say have been overlooked because of fierce competition between courier companies, according to Robert Gagel, branch manager for Choice Courier Systems of Washington. Gagel, who will be writing the bylaws for the group, said, "We are all faced with the same problems, and the formation of this kind of association in Washington is long overdue."

Courier companies agree that there is a need for a lobbying group such as the WMCA, but some are skeptical about bringing together so many competing couriers. Jeff Lodsun, a dispatcher for Co-Op Courier Services Inc., said it definitely would be the first time it was ever done and it probably would be difficult. But he said that employes of his company would attend the first meeting on June 4 to air their grievances, which center on the District's ticketing system.

Parking privileges, Metro fares and the industry's public image are a few of the concerns that will be heard at the meeting in Rosslyn, said Hess. With 80 couriers already among its ranks, the association hopes to come to some kind of agreement with the District's Department of Traffic Adjudication that would distinguish courier cars from other vehicles.

Sources in the industry agree that courier companies spend a lot of company time and money contesting traffic tickets. Hess said one suggestion is that the District issue an official decal that would make the distinction.

The association also plans to approach Metro officials about special rates for carriers who travel on foot. Hess said messengers on foot are an integral part of the New York City courier system, but in Washington the Metro fares are so high that it is not a reasonable alternative. Travel by foot would take the burden off couriers on bicycles and motor vehicles, who have trouble moving quickly from one end of the city to the other, he said.

As far as public image goes, Hess hopes the association will show the business community that many of the couriers, who may look like teen-agers, are professionals earning an average of $25,000 a year working for well-staffed companies.

A code of ethics or guidelines also will be drawn up by the association. "Our main objective is to make certain government agencies know that we exist and that we are attempting to approach business from a professional point of view," Gagel said.

The association is being formed by the association management firm of Smith Bucklin and Associates, Datrex and the law firm of Kornblut and Sokolove, which is in the process of drafting incorporation papers. TRADE

The National Paint and Coatings Association, based in Washington, is showing its true colors this month. In recognition of National Paint Month, the group and its affiliates will sponsor the renovation of a high school in Chicago, the renewal of a halfway house in Detroit, the repainting of a drug rehabilitation center for teen-agers in Oklahoma and a paint-a-thon in Denver, where community volunteers will paint hundreds of houses. The NPCA Picture It Painted Program was begun in 1980 to beautify buildings and show off the attributes of paint, in the spirit of the house-raising celebrations of old, a spokesman said. Judith Hittman, a spokeswoman for the association, said that the group welcomes suggestions from the community about houses or buildings that could be repainted or fixed up. In Washington on April 26, the association contributed paint to a project called Christmas in April, in which 1,200 community and corporate volunteers painted 56 houses. NPCA has more than 850 members that manufacture paints, varnishes, lacquers and other coatings.

At its annual meeting in Washington recently, the 70-year-old association representing cooperative businesses in this country elected its new officers. Frank B. Sollars, chairman of the Nationwide Mutual Insurance Co., who is also the owner of a 2,350-acre farm in Ohio and chairman of the board of the National Cooperative Bank, was sworn in as chairman of the National Cooperative Business Association. The NCBA represents cooperative business ventures in fields including fishery, insurance, health care, farming and agricultural marketing.

The Glass Packaging Institute has relocated its offices from McLean, where it has rented space for four years, to downtown Washington. A spokesman for the group said the move was made so association officials could get closer to member companies and government offices that are located inside the city limits.

The National Cable Television Association has promoted Larry A. Schott, its assistant director of state government relations since 1983, to director of association affairs. Schott will be responsible for member relations and development and will coordinate programs to aid state cable associations. PROFESSIONAL

The board of the National Association of State Savings and Loan Supervisors has selected the president of a local association management group as its executive director. William Drohan, who heads Drohan Management Groupin Virginia, also serves as the executive director of the National Association of State Credit Union Supervisors. Other recent appointments at the association include Paul Thomas as deputy executive director in charge of membership promotion and state agency program development and Phylis S. Bird, a former employe of the Amercan Bankers Association, as administrator in charge of convention management, educational programming and newsletter productions.