Though it's hard to argue against the merits of charity, Yugoslavian philosopher Slavoj Zizek's discussion on charity encourages probing more deeply into the ethical consequences of how people think about their personal acts of charity in modern capitalism.
Zizek sees modern capitalism, which he terms "cultural capitalism," as more than just an economic system. Under cultural capitalism, corporations are pressured not only to make money, but also to appease the cultural sensibilities of consumers. One such way of achieving this is through charity.
It is almost ubiquitous to see companies that offer some form of purchase-based charity; something along the lines of the company donating 10 cents for every purchase of its product. As Zizek sees it, this act of purchase (which is simultaneously charity) relieves the consumer of their own guilt and imperative to contribute to these good causes personally. Ultimately, such a system has the potential to damage worldwide charity overall.