While we’re debating about the reach of the NSA into our lives, perhaps a few thoughts about private-sector “snooping” might be in order, too. CBS This Morning‘s Charlie Rose and Norah O’Donnell interviewed WSJ reporter Elizabeth Dwoskin on the use of free wi-fi in retail environments for building profiles and tracking customers, a subject on which Dwoskin reported last week:

Mr. Zhang is a client of Turnstyle Solutions Inc., a year-old local company that has placed sensors in about 200 businesses within a 0.7 mile radius in downtown Toronto to track shoppers as they move in the city.

The sensors, each about the size of a deck of cards, follow signals emitted from Wi-Fi-enabled smartphones. That allows them to create portraits of roughly 2 million people’s habits as they have gone about their daily lives, traveling from yoga studios to restaurants, to coffee shops, sports stadiums, hotels, and nightclubs. …

But Turnstyle is among the few that have begun using the technology more broadly to follow people where they live, work and shop. The company’s dense network of sensors can track any phone that has Wi-Fi turned on, enabling the company to build profiles of consumers lifestyles.

Turnstyle’s weekly reports to clients use aggregate numbers and don’t include people’s names. But the company does collect the names, ages, genders, and social media profiles of some people who log in with Facebook to a free Wi-Fi service that Turnstyle runs at local restaurants and coffee shops, including Happy Child. It uses that information, along with the wider foot traffic data, to come up dozens lifestyle categories, including yoga-goers, people who like theater, and hipsters.

A business that knows which sports team is most favored by its clients could offer special promotions on game days, says Turnstyle’s 27-year-old founder Chris Gilpin. Czehoski, a local restaurant, hired an ’80s-music DJ for Friday nights after learning from Turnstyle that more than 60% of the restaurant’s Wi-Fi-enabled customers were over 30.

But as the industry grows in prominence, location trackers are bound to ignite privacy concerns. A company could, for example, track people’s visits to specialist doctors or hospitals and sell that data to marketers.

In other words, this happens whether one uses the free wi-fi internet service or not. If your smartphone has its wi-fi service on, Turnstyle (and presumably others in this industry) can track you anonymously and create profiles. If you want Internet connectivity, so much the better. The bandwidth consumers use is peanuts to the value of the data collected. More than one retailer offers coupons with scan codes when customers use their wi-fi service in the store, and it’s probably not difficult to match up the bar codes to the point-of-sale information and build very specific profiles from that information, too.

Most people probably understand that using these systems reduces their privacy, and are willing to trade off for the service. That’s certainly been true of free Internet services, such as e-mail. The extent of that intrusion may still surprise a lot of people, especially if they aren’t consenting as they do when signing up on Turnstyle’s Facebook site or the retailer’s web page.

Just remember this truth in the Internet age: If you’re not paying for the service, you’re not the customerIf that bothers people, they’d better be sure to turn off their wi-fi functions in public when they are not using them.