Archer Daniels Midland
The agricultural giant isn't terribly green.
While it's working on many biofuels, it has faced hundreds of millions of dollars worth of lawsuits for various types of pollution. According to Newsweek, it has big environmental impact, and a below average reputation.
Read more: http://www.businessinsider.com/the-15-worst-companies-for-the-environment-2009-9?op=1#ixzz3SFUF6uGH