Corporate America as a whole is blamed for all sorts of societal ills, from greed on Wall Street to shafting the little guy. But people's scorn can intensify when it comes to individual companies and other organizations, especially after inadvertent missteps or, worse, outright misconduct.

Here's a quick rundown of the 20 most hated U.S. companies, according to 24/7 Wall St., which took customer surveys, employee reviews and news events into account in devising its list: