I am going to go out on a limb here, but I would bet that sometime in the last 24 hours you have received a marketing message centered around how “green,” how “environmentally friendly,” or (if it’s really serious), how “sustainable” something is.

Whether or not we believe in these claims is a matter of some debate. The 2011 Cone Green Gap Trend Tracker found that an 97% of Americans believe they know what common environmental marketing claims such as “green” or “environmentally friendly” mean. Apparently we have seen enough of these claims to know what they’re all about.

But do we? Our interpretations are often inaccurate, according to the researchers. More than two in five of us (41%) erroneously believe that these terms mean a product has a beneficial impact on the environment. Only about one in three (29%) understand that these terms more accurately describe products with reduced environmental impact compared with competing products.

That study seems to indicate a lot of willingness to believe what the marketers tell us. However, a study from the U.K. has a somewhat different story to tell. In that study, by the Carbon Trust, only 7% of respondents take companies at their word when they say that they are reducing their climate impacts. More than half (53%) say they are concerned that companies make one-time improvements to win publicity, before returning to business as usual. Did the study ask different questions, or are the Brits more skeptical?

Sorting out the green from the greenwash has become a necessity for U.S. builders and designers. To help, my colleague Jennifer Atlee and I have developed a guide to common problems: we cleverly named it “Nine Types of Greenwashing” when we included it in our dare-I-say essential report on green building product certifications. We also have eagle eyes for these types of issues when we are setting standards and selecting green products for our GreenSpec product guide. Here are the nine types.

1.) Green by Association

A company slathers itself and its marketing thoroughly in environmental terms and images so that even if its products have no environmental benefits, consumers associate them with positive environmental attributes. Examples: Gas-guzzling cars and trucks pictured in remote natural settings, or housing developments named for natural features that they have destroyed, e.g., “Conifer Lane.”

2.) Lack of Definition

Marketing for a product makes an environmental claim that sounds good to the consumer but is too vague or general. Examples: a product is described as being non-toxic or without hazardous chemicals, when these definitions are only meaningful in specific contexts — many chemicals are non-toxic to the touch but harmful to ingest, for example. A radiant barrier paint product is advertised as having an incredibly high R-value, but the ad neglects to mention that it only insulates that well when installed on NASA spacecraft that see thousands of degrees of temperature differences.

3.) Unproven Claims

Environmental claims are made by a company, but the company cannot or will not provide evidence to back them up. Examples: A company claims to have implemented a new manufacturing process to increase its product’s recycled content, but doesn’t certify the claim. A manufacturer claims to have eliminated hazardous ingredients from a product but claims that due to trade secrets, it can’t reveal any specifics.

4.) The Non Sequitur

A company uses a valid claim about a product as the basis for a further claim that is not warranted, but may on its surface appear to be reasonable. Example: A manufacturer accurately claims that its product is resistant to mold growth, but also implies or states that thus using the product improves the health of occupants — a claim that has some logic, but that really needs to be evaluated separately.

5.) Forgetting the Life Cycle, a.k.a. The Red Herring

A company chooses one easily understood aspect of a product’s environmental profile to improve and highlight, while ignoring other significant impacts — sometimes out of ignorance; sometimes as an intentional effort to divert attention. Example: A company touts the high recycled content in its countertops, but it uses a lot of embodied energy and carbon to make them, and uses binders with human health impacts.

6.) Bait and Switch

A company heavily promotes the environmental attributes of a single product, while selling and manufacturing a bulk of otherwise similar products that lack the same environmental attributes. Example: A company sells cedar shingles that are certified as sustainably harvested, earning acclaim, but produces the product in such little volume at such an increased price that most of its sales resulting from the attention are for non-certified products.

7.) Rallying Behind a Lower Standard

A product earns an apparently valid, third-party certification — but the product’s manufacturer or trade association had influenced the development of the relevant standard in a way that makes the certification less meaningful than it appears. Example: The forest products industry catches hell in the early 1990s for environmental damages caused by logging, but rather than join the rigorous green standard that has already been developed, the industry bands together to create its own program with similar, but much more vague standards.

8.) Reluctant Enthusiast

A company lobbies against new environmental measures, claiming that they will be too costly. Particularly if it’s losing the battle however, it  hedges its bets, publicly embracing similar measures — while continuing to resist them behind the scenes. Example: “Beyond Petroleum.”

9.) Outright Lying

Either intentionally or inadvertently, a company bends the truth, or simply ignores it. Example: A company claims that a product is beneficial to the environment, when it’s actually just less bad. Or a manufacturer claims that its product contains recycled content based on reuse of scrap within a manufacturing line — but that actually doesn’t meet the definition of recycled.

I want to thank Terrachoice, which publishes the “Seven Sins of Greenwashing,” for helping inspire this list, which Jennifer and I first wrote over three years ago for our article, Behind the Logos: Understanding Green Product Certifications. We like their list, too, but we see some distinctions that we like to highlight.

What are examples of questionable green claims that you’ve seen recently? Want help evaluating them? Let me know.

Tristan Roberts is Editorial Director at BuildingGreen, Inc., in Brattleboro, Vermont, which publishes information on green building solutions. You can learn more at www.BuildingGreen.com.

Last week’s Energy Solutions post: New and Improved Cotton Insulation Still Doesn’t Work