Given the continent's colonial history, it's far from surprising that many Africans continue to weave a cloak of conspiracy theories about the role of the world's only remaining superpower in Africa.
Some are real (and hardly conspiracies), such as that the United States sees not just South Africa but Africa as a whole as an attractive investment destination, and that the US administration, like nearly all other foreign governments, hopes to further its business, and by extension, its political interests, on the continent through a combination of trade and aid.
Others are largely imagined, such as that "the Americans" and their president, as one protester at the University of Johannesburg put it, are "here for our African resources", adding "hands off our gold, oil, diamonds and land". Or that the US military is subtly recolonising Africa through its Africom bases and hopes somehow to turn South Africa into a bastion of American imperialism.
Indeed, at last year's Mangaung conference, the ANC said it would "play an active role in African networks campaigning against Africom".
Which is all well and good – until there's trouble. Then it's discovered that "the Americans" have their uses after all. Whether it's dishing out billions of dollars in aid (as it does to South Africa), providing law-enforcement and antiterrorism training to underqualified locals (the FBI trained the Scorpions) or stepping in militarily to save the day, as the US is being pressured to do in Syria, anti-Americanism makes for good protests and sloganeering. But it does the country, and indeed the continent, no favours.
There is a more than slightly two-faced nature to the anti-American protests, which are a defining feature of the so-called antiglobalisation or anti-new world order movement.
They condemn the US for being the overbearing, overreaching "world's policeman" but, when it comes to asking for economic hand-outs or a projection of military power (against Muammar Gaddafi and now Bashar al-Assad), the first question asked is: "Where are the Americans?"
It goes to the heart of the role played by the US in the world today: a country that is damned if it does, and damned if it doesn't.
Indeed, as Shakespeare's Henry IV lamented when facing rebellion in the ranks: "Uneasy lies the head that wears a crown."
Many of the protests against President Barack Obama's visit focused on the US's foreign policy, particularly in the Middle East, and related to the so-called war on terror – which is not surprising, given that country's recent list of military misadventures in the region, as well as in Afghanistan.
The controversial drone programme and the continued existence of the detention camp at Guantanamo Bay make it hard to dispute what one poster brandished at the protests said: "American democracy stinks of hypocracy [sic]".
But, then again, so does anti-Americanism, and its counterpart, Sinophobia.
The US is the world's largest bilateral aid donor, with South Africa being one of the largest recipients of US foreign aid. In addition to trade-friendly legislation such as the African Growth and Opportunities Act, US aid almost single-handedly saved South Africa's Aids treatment programme.
The President's Emergency Plan for Aids Relief initiative, commissioned by the George W Bush White House, continues to support care and treatment in South Africa, shouldering a vast financial burden that it's doubtful South Africa's health department could have done alone.
USAid continues to fund innovative programmes in sustainable agriculture, education and training in South Africa, and included the start-up of the popular children's show Takalani Sesame.
Nobody is denying anyone the right to protest or suggesting that, as "grateful Africans", we should just shut up and clutch our begging bowls. Nor is gratitude for US largesse necessarily incompatible with speaking out against its perceived excesses.
But those who would give in to what Slavoj Zizek once called a "utopian impulse" and take to the streets would have far greater impact if they looked beyond easy sloganeering and at the real issues. Like calling for fairer trade deals that would make access to US markets easier for South African products, or calling for greater transparency and better corporate governance to ensure that US aid to this country (and it runs into billions) is properly spent and not mismanaged, which in the current climate, where corruption in government is at a high, is not impossible.
On a military level, South Africa has long been lobbying for an African country to have a permanent seat on the United Nations Security Council. But as Obama rightly said, many want a seat at the table but not all want the responsibility that comes with it, particularly the financial one, and that of taking the blame when there are failures.
There is in some quarters also disappointment in Obama personally that, as a black American with African roots, he has failed to measure up to his pre-election rhetoric. That may be, but it is a long stretch to suggest that the US is the most oppressive country around, as is being suggested by protesters who carried the posters favoured by the American right – of Obama with a Hitler-style moustache.
There are countries with far less savoury reputations with whom we do business, countries literally "beyond corruption", for whom human rights, women's rights and the like are nonexistent for all but the privileged.
Yet their military-hardware shopping trips to South Africa pass with barely a comment.
Anti-Americanism and Sinophobia are a chimera that our government should help to disabuse our professional protesters of. We need the US with its aid (and its weapons) far more than it needs us.