I think the Kochs are unduly vilified. They are as much to blame for any problems within the libertarian movement as Rothbard is, who was a polarizing figure himself. Overwhelmingly they are to be commended for their advocacy of libertarianism.
From the wiki article about Charles Koch (notice his appreciation for Mises and Hayek and his deep understanding of the philosophy of libertarianism):
Koch's views are described as libertarian. He disliked George W. Bush's presidency. His favorite presidents are George Washington, Grover Cleveland, and Calvin Coolidge.[16]
He told the National Journal that his "overall concept is to minimize the role of government and to maximize the role of private economy and to maximize personal freedoms."[17] Today, he worries about too much governmental regulation, writing, "We could be facing the greatest loss of liberty and prosperity since the 1930s.".[18]
In an interview with the American Journal of Business,[10] Koch said he owes "a huge debt of gratitude to the giants who created the Austrian School [of economics]. They developed principles that enabled me to gain an understanding of how the world works, and these ideas were a catalyst in the development of Market-Based Management." In particular, he expresses admiration for Ludwig von Mises’ book Human Action, as well as the writings of Friedrich von Hayek.
Other influences on Koch include Alexis de Tocqueville,[19] Adam Smith, Michael Polanyi,[10] Joseph Schumpeter, Julian Simon, Paul Johnson, Thomas Sowell, Charles Murray, Leonard Read, and F.A. Harper.[11]
To Koch, "the short-term infatuation with quarterly earnings on Wall Street restricts the earnings potential of Fortune 500 publicly traded firms".[11] Koch also considers public firms to be "feeding grounds for lawyers and lawsuits", with regulations like Sarbanes–Oxley only increasing the earnings potential of privately-held companies.[11]
In an interview article for the Wall Street Journal, Stephen Moore writes "Charles Koch—no surprise—disdains government and the political class."[11] Koch thinks the billionaires Warren Buffett and George Soros, who fund organizations with different ideologies, "simply haven't been sufficiently exposed to the ideas of liberty".[11] Koch thinks "prosperity is under attack" by the Obama administration and "warns of policies that 'threaten to erode our economic freedom and transfer vast sums of money to the state'".[20]
In an op-ed for the Wall Street Journal Koch said: “Government spending on business only aggravates the problem. Too many business have successfully lobbied for special favors and treatment by seeking mandates for their products, subsidies (in the form of cash payments from the government), and regulations and tariffs to keep more efficient competitors at bay. Crony capitalism is much easier than competing in an open market. But it erodes our overall standard of living and stifles entrepreneurs by rewarding the politically favored rather than those who provide what consumers want.”[21]