NAD was faced with that very question in a recent NAD challenge brought by Kimberly-Clark against competitor Dyper. 

In the case, Kimberly-Clark took issue with a handful of claims Dyper made about its diaper products, including claims that Dyper diapers are "biodegradable" and "feel more like yoga pants" (I don't know about the babies in your life, but my 16-month-old niece does love a good yoga pant...)

Kimberly-Clark argued that Dyper's "biodegradable" claim was deceptive because it was not properly qualified to communicate the limited availability of appropriate composting facilities. Specifically, the challenger argued that Dyper's curbside pickup composting service, "REDYPER," is unavailable to a large majority of consumers, and that for those who do not have access to REDYPER, industrial composting facilities that accept biohazardous waste are not generally available. As such, Kimberly-Clark asserted that the vast majority of Dyper diapers will be disposed of in landfills where they will not biodegrade.

Despite Dyper's argument that the REDYPER service is utilized by 8,000+ customers every month (and is offered for an additional fee as a mail-away service in markets where it does not otherwise operate a pickup program), NAD found that Dyper's "biodegradable" claim could still be misleading. 

Citing to the Green Guides for the proposition that "degradable claims should be qualified clearly and prominently to the extent necessary to avoid deception about: (1) the product’s or package’s ability to degrade in the environment where it is customarily disposed; and (2) the rate and extent of degradation," NAD noted that "not all Dyper customers presently use the REDYPER program... there are cost, space, and time factors that could also constrain use of the REDYPER service...[and] there are a limited number of industrial sites that accept solid municipal waste..." As such, NAD recommended Dyper further qualify its "biodegradable claim."

On the yoga pants claim, NAD agreed with Dyper's argument that the claim was whimsical in nature and an obvious subjective statement that was incapable of being proven literally false. NAD determined that the claim wouldn't present an meaningful analogy to consumers so, instead, they would see it as a fanciful comparison and wouldn't expect substantiation for the claim. 

NAD Case Reports #7144