On December 7, 2016, Eric Ball & William Pierog of Fenwick & West published a very useful and well-researched article, “Can Internet Comments and Search Results Prove Trademark Infringement?”
The article explores what types of comments will and will not help prove confusion, backed by citations to particular cases in which the issues have arisen.
[O]nline comments… are not hearsay if they… are not offered for the truth of the matter asserted… [and instead…[are] offered to show assumed association between the parties.
…evidence that does show confusion about product source may only suggest that the internet user “appears to be someone so easily confused that even trademark law cannot protect her.”
…inattentiveness during purchasing decisions is relevant…[but] consumer inattentiveness at other times may not suggest product source confusion.
[Concerning search results as evidence of confusion]…Consumers expect a search to return unrelated products.
…evidence should be from relevant purchasers rather than vendors or third-party businesses.