An independent spyware analyst is accusing Yahoo of supporting spyware companies by distributing Yahoo Search Marketing ads to them.

Consultant Ben Edelman faulted Yahoo for not letting its advertisers know where their ads might end up.

"We know people pay very high pay-per-click fees when they think they're getting traffic from Yahoo, because advertisers think Yahoo users are more valuable," Edelman told internetnews.com. "Whatever their value actually is, advertisers who are buying the stuff should be told what they're getting."

Adware is free ad-supported software that users can download at no charge. But in his blog, Edelman documented how the software is installed without clear notification.