A site billing itself as the world's largest sex and swingers community has settled charges with the U.S. Federal Trade Commission that it bombarded consumers with sexually explicit pop-up ads.

The owners of AdultFriendFinder.com were accused of pushing the ads through spyware that was often installed without consumers' knowledge, the FTC said in a complaint set to be filed Thursday in federal court. Victims who had never even visited sexually explicit sites would suddenly find themselves face to face with full-screen pornographic ads after typing innocuous sounding terms such as "flowers," "travel," and "vacations" into search engines.

The site's operator, Various Inc. of Palo Alto, California, has agreed to clean up its marketing practices and require consumers to give their consent before ads are displayed, and to set up a Web site where consumers can submit complaints. "The settlement bars the defendant from displaying sexually explicit online ads to consumers who are not seeking out sexually explicit content," the FTC said Thursday in a statement .

No fines were imposed as part of the settlement, Various' first with the FTC, and the company has admitted no wrongdoing. Federal law prohibits the FTC from imposing fines on first-time violators.

Various' other Web sites, such as Cams.com, Passion.com, and NudeCards.com, are also covered by the terms of the settlement.

Spyware researcher Ben Edelman says that unwanted pornographic ads are a widespread problem. "Unrequested displays of sexually-explicit content largely arise out of the unaccountability pervasive in the spyware space," the Harvard Business School assistant professor wrote in a June 2006 post to his Web site , which documented a number of examples of the problem.

Because of the way that spyware is disseminated it is easy for the parties involved to blame each other for the pop-up ads, he said. "Ad networks may claim that other ad networks told them... that traffic was suitable for sexually-explicit ad display. Spyware vendors will blame other spyware for having suggested that users wanted such content. In all likelihood, no party will take responsibility," he wrote.