Ultimately, corruption ruins each idealogy. In communism corruption is on a widespread scale since *anybody* who works for the government is in a relatively powerful position (when compared to non-government workers), but the amounts paid per corrupt act are probably not huge. The 50 whatevers to the housing attendant to jump you up the housing list, the 50 to the local cops to avoid being arrested on completely fabricated charges etc.
In capitalism, the corruption is far less widely spread, as government is smaller and less powerful, and business is bigger and more powerful. The damage is just as great - laws being passed to help big business in return for a campaign donation that help the big corporations but rip off the public - eg DCMA, the 'Mickey Mouse' Act of 1976, etc. And let's not forget the carefully woven webs of decit that have brought down Enron, Arthur Andersen, Worldcom, Tyco etc, robbing people of their jobs and pensions, while the CEOs get very rich. I cannot believe that those scandals could be perpetuated without some wheels being greased along the way.