How would you respond if you had paid Google $136.11 for advertising that appeared not on quality sites like The New York Times, but on parked domains and error pages? If you were lawyer Hal Levitte, you might file a federal lawsuit in California over Google's behavior and then seek class-action status for the claim.

That's exactly what Levitte did on July 11, when his lawyer filed a complaint against Google (first reported by Information Week). The complaint, a copy of which was provided to Ars Technica, argues that Google is guilty of "unjust enrichment" by promising high-quality ad placements and then serving a substantial portion of ads on low-quality sites.

Levitte learned this the hard way in 2007, when he mounted an $887.67 campaign to promote his law practice's web site. Levitte hoped the click-throughs would generate phone calls, e-mails, and filled-in online forms, but he was surprised at the number of clicks that came from parked domains and errors. According to the lawsuit, 16.3 percent of all the clicks in the campaign came from such sites, but not a single one of those clicks led to a conversion.

"These websites result in a lower conversion rate than standard search traffic or websites with actual content on them," says the complaint.

The suit claims that it was difficult to opt out of having ads placed on such sites until March 2008; after that date, Google provided a way to opt into third-party sites while excluding error sites and parked domains, but this option was buried "four clicks deep within [Google's] interface, where many advertisers would not notice it."

Levitte claims that Google never made clear to him that his ads would appear on error sites and parked domains and is guilty of fraudulent advertising. He contacted the company, which looked into the situation and determined that the clicks which had come from those parked and error sites were legitimate, even if they resulted in no conversions.

Although the policy has since been changed, and although Levitte only spent about a hundred dollars on such sites, his suit seeks class-action status for everyone in the US with an AdWords account over the last four years (assuming that at least one ad impression appeared on a parked or error site). If the judge allows it, that could be a terrifically large class.