THE first rule for public-relations firms is not to become the story. In South Africa Bell Pottinger, a British firm, has done just that. In May, e-mails between one of the firm’s employees and Duduzane Zuma, a son of President Jacob Zuma, were leaked to South African newspapers. Bell Pottinger had been hired by a company owned by the Gupta family, a trio of Indian businessmen brothers who are chummy with the president, to bolster their image.

One can see why they might seek such help. A report by a former public protector last year accused them of orchestrating “state capture” on behalf of the president, and their names have become a campaign slogan for the opposition. The e-mails showed how the firm had proposed to push the idea that criticism of the president—and the Gupta family—was intended to perpetuate “economic apartheid”, an incendiary claim in South Africa.

After a barrage of criticism, on July 6th the firm apologised and said it had sacked one of its partners. Their critics are not satisfied. The Democratic Alliance, South Africa’s main opposition party, continues to organise protests outside Bell Pottinger’s offices. Lord Bell, the firm’s founder (who left last year), told a magazine that he always thought the work in South Africa was “smelly” and that the chief executive must have known what his firm was doing.

Western firms have long offered help to shady leaders wanting to gild their reputations overseas. Increasingly, however, they are being drafted to run domestic political campaigns too—spreading deft propaganda via social media. Bell Pottinger is far from the only firm spinning south of the Sahara. In Kenya, Cambridge Analytica, a firm credited with helping Donald Trump become president, is working to help President Uhuru Kenyatta get re-elected. In Gabon last August, a country with a population of less than 2m, your correspondent encountered no fewer than three firms working on the re-election campaign of President Ali Bongo Ondimba.

This work is lucrative. In America, lobbying firms working for foreign governments must submit details of their deals under the Foreign Agents Registration Act (FARA). These show, for example, how Moïse Katumbi, an exiled politician from the Democratic Republic of Congo, paid $350,000 for the services of Akin, Gump, Strauss, Hauer & Feld. The Congolese government, too, has its own firm. FARA returns show that 15 countries have contracts with American lobbying firms. There is no equivalent disclosure in Europe.

The work is also controversial. “Those who succeed are the ones doing the dark arts,” says one consultant. Cambridge Analytica refuses to say what it is doing this year in Kenya, but many Kenyans suspect it is helping to craft a vicious campaign. In the 2013 Kenyan election, it claims its research made it “able to draft an effective campaign strategy” for Mr Kenyatta. That election was widely suspected of having been rigged. During the campaign Mr Kenyatta’s team seemed to suggest, absurdly, that the British government was planning to use military force to stop him winning.

Bell Pottinger is not the only firm to be embarrassed. On December 26th last year, in Congo-Brazzaville, state media jubilantly announced that the president, Denis Sassou-Nguesso, would be one of the first world leaders to meet president-elect Donald Trump in Florida. One TV channel even showed a fake picture of the pair embracing. A FARA file showed that the coup was the work of a Romanian PR firm, Global Structures Group, hired to “improve Congo’s image abroad”. Sadly for Mr Sassou-Nguesso, after a storm of criticism, the White House denied that it had ever agreed a thing.

Is operating in Africa worth it? For Bell Pottinger the answer seems probably not. But few African countries have as energetic an opposition or press as South Africa; in other countries, it is easier to stay in the shadows. Perhaps the bigger question is whether it is worth it for the people paying. Nicholas Cheeseman of the University of Birmingham reckons that a lot of firms are selling snake oil. “I have yet to meet many consultants [who] actually understand how African elections work,” he says. Perhaps the best hope is that they change how the outcomes are perceived abroad: no small thing on a continent where campaigns are often bitter and results often disputed. Your correspondent will do his best to avoid being influenced.