However, as you’ve had plenty of time to notice, the shop advertises that it donates 15% of its profits to an organization that’s working on saving the rainforest. Do you a) overlook the lousy service? Or b) vow never to return and to tell your friends how bad it is?

If saving the rainforest is a cause you care about, you probably answered a). At least, that’s one conclusion of a new study in the Journal of Public Policy & Marketing. “When firms support good causes, they accrue moral capital and create a reservoir of goodwill,” says Jeff Joireman, an associate professor of marketing at Washington State University who led the research project.

That goodwill makes people much more inclined to put up with even truly abysmal customer service, the study found, and to refrain from spreading negative buzz about the business. What’s more, customers are most likely to put up with ill treatment when they get to choose which worthy cause their purchase will help.

The researchers conducted two experiments on volunteers who were first tested to find out how high (or low) they scored on concern for the environment. Then, the group was split into three smaller groups and told either that the hypothetical shop, called The Coffee Bean, gave 15% of its profits to environmental causes, that it donated 2%, or they were told nothing. Everyone was kept waiting an inordinately long time for their coffee, and then given the wrong kind.

Without fail, “customers” who scored high on concern for the planet and who were told about the shop’s support for the environment were far less angry than anyone else. Moreover, those who thought the shop donated 15% were the most forgiving and told researchers they might return in the future despite the crummy service. Some even “expressed guilt at the thought of harming” the coffee shop by badmouthing it to others, the study says.

Researchers noticed that the volunteers who had scored lowest on concern for the environment were the most outraged over the bad service they received and the most inclined to spread negative word of mouth about it. “We saw a backlash from those customers,” Joireman notes, “because of the mismatch between the company’s values and their own.”

So the second part of the study was designed to cut down on the possibility of such a mismatch. Joireman’s team told one group that a percentage of their purchase would go to saving the planet. A second group was given a choice of four different worthy causes, just one of which was “green”; the other three were medical and civic charities. As with the first experiment, a third group heard nothing.

This time, the people who were allowed to choose a charity were by far the most tolerant of shabby treatment, expressing “markedly less anger than anyone else about the bad service, and an even greater reluctance to say anything negative about the business,” Joireman says.

“The implication for marketers is clear. Instead of trying to guess which one cause the most customers will get behind, give them a choice,” he adds. “Even when it comes to good deeds, people love choice.”