Corporate America has discovered that going green is the way to sell products these days. Sales of organic products have gone from $10 billion in 2003 to more than $16 billion in 2006. Products advertised as being sustainable or healthy accounted for more than $200 billion in U.S. sales in 2005.

But as legions of marketers make “green” pitches ranging from earnest to ridiculous, customers are growing warier.

Environmentalists welcome genuine corporate efforts to make products more benign, but there’s a fine line between real environmental efforts and "greenwashing." Last year, a Philadelphia marketing firm called TerraChoice investigated more than 1,000 products claiming to have some environmental benefit. All but one of them committed one of what the company dubbed the "Six Sins of Greenwashing", such as hidden problems or vague claims.