• by Wendy Davis , Staff Writer @wendyndavis, June 26, 2012

If you visit Orbitz.com and search for hotels, the offers you're shown might differ depending on whether you're using a Mac or a PC. Specifically, if you're using a Mac, the travel site sometimes shows pricier options than if you're using a PC, according to a report in today's Wall Street Journal.

Orbitz.com tells the Journal that people can always configure the results to prioritize hotels based on price. The company also tells USA Today that the different offers only appear in a screen that says "recommendations for you," which is shown to users who have already clicked on a hotel.

Orbitz says it began personalizing results based on computer after noticing that Mac users tend to book more expensive hotel rooms than PC users. And, while Orbitz shows Mac and PC users different recommendations, it isn't quoting people different prices for the same hotel rooms.

While the program might make perfect sense to Orbitz, many observers take issue with the company's decision. In fact, judging by today's headlines, Orbitz is fast on its way to becoming poster child for everything people find creepy about online advertising.

That "creepiness" might in itself be cause for concern, says Ryan Calo, a privacy expert with Stanford Law School's  Center for Internet and Society. "The fact that people are creeped out by this is legitimate, and itself registers as a privacy harm," says Calo. He adds that if people don't understand how sites are arriving at prices, or feel like they're being manipulated, they might stop transacting business online.

Of course, in the offline world, some salespeople can and do size up consumers and then quote prices based on what it looks like people will pay. The difference, says Calo, is that people can figure out when that's likely to happen and control for it. "If you go to a car dealership wearing a big, flashy Rolex, you should have known better," Calo says.

But Web users have no realistic way of predicting that a site like Orbitz.com will return different results based on the type of computer they're using. And it's not like everyone can change computers as easily as they can change accessories.

"You can't just look at this in isolation," Calo adds. "It's a dangerous road to go down, because I believe that what's at the end of that road is companies putting their consumers at a disadvantage."

But Jules Polonetsky, co-chair and director of the think tank Future of Privacy Forum, says the problem isn't that Orbitz customized results, but the fact that it didn't alert users in advance. He says that users might not object if Orbitz told them, "We think you're a luxury traveler. These options are for you."

"When users are surprised to find out that things are personalized, they often feel that something is being slipped past them," he says. "When users are aware that personalization is happening, that they're being catered to, they end up finding it valuable."