From www.terrachoice.com

Green-wash (green'wash', -wôsh') – verb: the act of misleading consumers regarding the environmental practices of a company or the environmental benefits of a product or service.

Sin of the Hidden Trade-Off - e.g. paper (including household tissue, paper towel and copy paper): “Okay, this product comes from a sustainably harvested forest, but what are the impacts of its milling and transportation? Is the manufacturer also trying to reduce those impacts?” Emphasizing one environmental issue isn’t a problem (indeed, it often makes for better communications). The problem arises when hiding a trade-off between environmental issues.

Sin of No Proof - e.g. Personal care products (such as shampoos and conditioners) that claim not to have been tested on animals, but offer no evidence or certification of this claim. Company websites, third-party certifiers, and toll-free phone numbers are easy and effective means of delivering proof.

Sin of Vagueness - e.g. Garden insecticides promoted as “chemical-free.” In fact, nothing is free of chemicals. Water is a chemical. All plants, animals, and humans are made of chemicals as are all of our products. If the marketing claim doesn’t explain itself (“here’s what we mean by ‘eco’ …”), the claim is vague and meaningless. Similarly, watch for other popular vague green terms: “non-toxic”, “all-natural”, “environmentally-friendly”, and “earth-friendly.”

Sin of Irrelevance - e.g. CFC-free oven cleaners, CFC free shaving gels, CFC-free window cleaners, CFC-disinfectants. Could all of the other products in this category make the same claim? The most common example is easy to detect: Don’t be impressed by CFC-free! Ask if the claim is important and relevant to the product. (If a light bulb claimed water efficiency benefits you should be suspicious.) Comparison-shop (and ask the competitive vendors)

Sin of Fibbing - e.g. Shampoos that claims to be “certified organic”, but for which our research could find no such certification.
When I check up on it, is the claim true? The most frequent examples in this study were false uses of third-party certifications. Thankfully, these are easy to confirm. Legitimate third-party certifiers – EcoLogoCM, Chlorine Free Products Association (CFPA), Forest Stewardship Council (FSC), Green Guard, Green Seal (for example) – all maintain publicly available lists of certified products. Some even maintain fraud advisories for products that are falsely claiming certification.

Sin of the Lesser of Two Evils - e.g. Organic tobacco. “Green” insecticides and herbicides.
Is the claim trying to make consumers feel ‘green’ about a product category that is of questionable environmental benefit? Consumers concerned about the pollution associated with cigarettes would be better served by quitting smoking than by buying organic cigarettes. Similarly, consumers concerned about the human health and environmental risks of excessive use of lawn chemicals might create a bigger environmental benefit by reducing their use than by looking for greener alternatives.