On the other hand, it can be a tough sell.
Consider some recent headlines. There were union ironworkers charged with racketeering and union electricians picketing a well-known developer in Northwest Philadelphia. Last summer, a nasty developer vs. union battle made news.
In the last two weeks, union carpenters and Teamsters have been ousted from the Convention Center in a highly publicized dispute over whether the two unions added cost and hassle, discouraging groups from booking shows there.
In fairness, the ironworkers are innocent until proven guilty, and there are two sides, and maybe more, to every picket line.
But marketing relies as much on impression and stereotype as on fact - a challenge to unions and contractors seeking a bigger piece of the construction pie in a recovering economy.
"Negative publicity is not something we seek out. Obviously, that's nothing that helps," said Kevin Hilton, chief executive of Impact, a national marketing and education organization jointly funded by union ironworkers and union contractors.
"This is the moment in history for us to make a huge rebound" and land new business, he said.
In their pitches, unions and contractors point to worker training programs. U.S. Labor Secretary Thomas Perez recently visited and praised the Finishing Trades Institute, the apprentice training center in Northeast Philadelphia run by the International Union of Painters and Allied Trades District 21.
Marketing efforts are a must, for both the unions and union contractors, if they want to capture and retain building share from their nonunion competitors, Hilton said.
What unions and contractors have had in common, he said, was a certain gruff reluctance to engage in modern marketing.
Their tools are cranes and wrenches, he said, not websites and marketing.
This year, drivers on I-95 could spot a billboard jointly funded by electrical contractors and the electricians' union promising top-notch work.
In February, the same month the ironworkers were indicted, Hilton's organization by coincidence hired a new marketing maven. Joe Matos' bio listed top advertising agency experience promoting key brands such as Gatorade and Toyota.
Last week, 45 engineers and architects attended the Coatings and Corrosion Academy at the Finishing Trades Institute.
Free lunch and professional credits were included in the event co-sponsored by the painters' union and the Delaware Valley Industrial Painters Alliance, a group of union contractors who paint bridges and refineries.
The goal was to teach the latest techniques while showing off the school and making a point about the expertise of union workers and their employers.
And in July, Philadelphia will host the first GlassCon Global Conference in North America, presenting new technologies in architectural glass and glazing.
The conference is sponsored by the Finishing Contractors Association, a national association of union contractors.
Some of the conference-organizing work in Philadelphia is being handled by Stephanie Staub, marketing director of Philadelphia's Architectural Glass Institute. The local glaziers' union and area union contractors jointly hired Staub to promote their companies and workers.
"Many unions weren't doing this before," she said, talking about her job. "Marketing to the end user is getting very common. It's definitely a trend."
Steven S. Lakin, who heads the General Building Contractors Association, says his organization's advertisements are intended to tell the end user - owners and developers - that its contractors have the equivalent of the Good Housekeeping Seal of Approval for excellence
"We didn't embark on this campaign to offset public perception about unions," Lakin said.
One potential customer for contractors, union or not, is Ken Weinstein, a Philadelphia developer.
Angered by his unwillingness to use union electrical contractors on some projects, members of Local 98 of the International Brotherhood of Electrical Workers have persistently picketed Weinstein's Trolley Car diner in Mount Airy.
"Ken Weinstein is a greedy profiteer," wrote Jim Snyder, Local 98's assistant business manager. The union is "conducting a peaceful, lawful protest at his businesses because he is violating area wages and benefit standards."
Weinstein said he's "very pro-union."
"But these guys aren't a union," he added. "This is an exclusive membership club. They just hire their friends and relatives."
That kind of sentiment raises the ire of Local 98's leader, John J. Dougherty, who said that during the "toxic week" after the ironworkers' indictment, he made the rounds to describe how union workers help the community.
Union electricians, he said, wired Boathouse Row and repaired homeless shelters at no charge.
"We have done a terrible job marketing ourselves," he said, promising more marketing efforts in the future. "We're not going to be on the defensive."