Two more additions to online advertising's hall of shame: Bolt.com and Orbitz. The teen community site and the travel booking engine have both inflated their audience numbers by "popping up" pages of their sites on the screens of unwitting internet users, according to a new study. It's a sign that some big-name internet publishers, desperate to grab a bigger piece of buoyant online revenues, are using underhand tactics to appear more impressive to potential advertisers. This is the online equivalent of an offline publisher dumping thousands of magazines on doorsteps, and claiming those copies as part of circulation.

Ben Edelman, a researcher into spyware at Harvard Business School, says Bolt.com, which claims 15m unique visitors each month, was referred traffic by Paypopup, a marketing agency known for tricking internet users into visiting sites. Away.com, part of the Orbitz online travel group, received traffic via Web Nexus, another agency, this one registered in Bosnia, known for running pop-up advertising without a user's consent.

Bolt and Orbitz are by no means alone. Edelman earlier identified other culprits: Heavy.com, the video humor site, Conde Nast's travel site and one of the leading online business titles, Forbes, which is owned in part by Roger McNamee's Elevation Partners. It's typical for these companies to say that they used marketing agencies to attract new users, but didn't know they were in turn connected with less reputable internet marketers, such software distributors which sneak spyware onto users' computers, to spawn unwanted ads. That's simply not credible: if the publishers claim ignorance, it was simply because they chose not to discover how the traffic was obtained.

Edelman's discovery isn't simply embarrassing for these publishers; it has the potential to damage their advertising business. For instance, Verizon has a stated policy, that it does not advertise on pages spawned without a user's consent — a policy contravened by its banners on Away.com.

Below, the hall of shame: the brand-name online publishers which have inflated traffic with pop-up pages of their sites. They're welcome to respond, and explain their actions, in the comments.

Heavy.com

Forbes
Concierge.com
Bolt Media
Orbitz