• by Laurie Sullivan , Staff Writer @lauriesullivan, May 25, 2012

Editor's Note: This story has been updated to reflect a change in the white paper. One of the earlier versions listing the top 10 cookie stuffers included couponcactus.com. It no longer does. The lastest list follows: No. 1: ShopAtHome.com; No. 2: We-care.com; No. 3: Socialingot.com; No. 4: Free-Causes.com; No. 5: Interesting.cc; No. 6: Cltrda.com; No. 7: DropInSavings.com; No. 8: RebateGiant.com; No. 9: DeedorGreed.com; and No. 10: ExtraBux.com. Marketers can download the white paper here.

Convertro, a cross-channel marketing and optimization company, plans to publish a white paper on cookie stuffing, a phenomenon where marketing affiliates insert their code to receive credit for traffic that would have gone to a company's Web site anyway.

Considered by many as a black hat-type online marketing technique, this process brings visitors to the Web site through a third-party piece of data stored in the browser with or without their knowledge.

The white paper names the top 10 cookie stuffers based on a list of criteria, including size, reach and traceability of the stuffers. Size must be a minimum of 30 cookie stuffing incidents daily per URL. The reach must include at least three or more different clients with affiliate cookie stuffers. Traceability is the ability for Convertro to identify the cookie stuffer. The problem is that many cookie stuffers use blank referring URLs, making it impossible to identify the stuffer by name. Only the publisher ID is available.

The paper also explains the techniques used to track online activity so search marketers can learn about what Convertro calls affiliate program scams. Attribution marketing techniques and technology for both online and offline channels can capture this type of data.

Generally, the techniques of the company on the list have several things in common. Merchants pay for clicks they would have received without the help of the affiliate. Most of the cookie stuffers tap into browser toolbars or plug-ins, according to the white paper. The other common themes include users installing the toolbar in exchange for a revenue share, or cash back; donation to a charity; or coupons.

Narrowed down from 50 candidates, Convertro names shopathome.com as the No. 1 cookie stuffer and s3pr.freecause.com at No. 2, followed by plugin.we-care.com, 365koopons.com, dropsavings.com, socialingot.com, deedorgreed.com, rebategiant.com, extrabux.com, and couponcactus.com.

Aside from identifying the companies, Convertro details the cookie-stuffing method and any known affiliate IDs. For example, at shopathome.com users log in and download a toolbar. The toolbar opens whenever a user goes to a site that is part of the affiliate network, even if they enter the site by directly typing the domain into the browser or through a search engine. The toolbar offers coupons for products on the site. Sometimes the coupons offer extra savings, but other times they are standard offers the consumer would get without it.

On some sites, if the user clicks to reveal the coupon without committing to use it or buying anything, their browser is redirected to a URL with the affiliate ID. This is cookie stuffing, according to the white paper.

The known cookie stuffing for we-care.com relies on the consumer becoming a member. If the consumer buys through this toolbar they will donate a percentage of their purchase to a charity of their choice. The toolbar also inserts a hearts and an animated dog on the Google search page next to the brand's organic listing. In this case, the white paper explains if this link is clicked on the we-care affiliate program gets a commission.