If a proposed trademark or service mark is not inherently distinctive, it may be registered on the Principal Register only upon proof of acquired distinctiveness, or "secondary meaning." In order to establish secondary meaning, there must be evidence that, the primary significance of the trademark or trade dress in the minds of the consuming public is not the product but the producer.J. Thomas McCarthy states that, “one of the most scientific methods of the mental associations of the consuming public is to conduct a survey of the purchasers themselves.” In fact, consumer surveys are considered by several circuits to be the most direct and persuasive evidence of secondary meaning. 
Some secondary meaning survey examples include, but are not limited to:
Establishing Protection for a Product Design or Configuration
For decades, Hershey’s has manufactured chocolate bars bearing a design mark which consists of a rectangle containing 12 equally sized panels with the HERSHEY’S mark arranged in a four-by-three format. Hershey’s already had a trademark product design registration using the name HERSHEY’S within the rectangular panels but sought protection for the generic configuration.
A secondary meaning survey conducted by AMS survey expert Bob Klein measured the extent to which relevant consumers associate the four panel by three panel appearance of the candy bar with a single source. The results of the Klein survey showed that the product configuration had indeed acquired secondary meaning. The Final TTAB decision approved the registration of Hershey’s application and cited the Klein survey as “persuasive evidence” in establishing secondary meaning.
Challenging the Validity of an Existing Mark
Media personality Christopher Kimball planned to open a new business venture called Milk Street Kitchen in Boston. Milk Street Cafe, a café and catering company located in Boston, filed a lawsuit against Milk Street Kitchen alleging reverse confusion and that Milk Street Kitchen, although the newer of the two businesses, would cause Milk Street Cafe harm by infringing its trademark. Milk Street Café countered that Milk Street Kitchen’s mark was improperly issued, has not achieved secondary meaning and was geographically descriptive, and sought to have registration for the mark cancelled.
Defendant Milk Street Kitchen retained AMS survey expert Brian Sowers to conduct a secondary meaning survey to assess whether relevant consumers associate the Milk Street Cafe trademark with a single source. The results of the Sowers survey showed that the mark had, in fact, not acquired secondary meaning. The court’s decision, citing the survey and Sowers’ “thorough and credible” testimony at trial, found that the Milk Street Café mark was “merely descriptive and has not acquired secondary meaning.”
These are just a few examples of the many ways in which secondary meaning surveys have been relied upon by the courts. To learn more about AMS or secondary meaning surveys, please contact us.
 McCarthy on Trademarks and Unfair Competition § 15:42 (5th ed.)