These days video cameras pan every supermarket, big-box store parking lot and even some school buses. Americans aren't paranoid; they know someone is watching. And many don't mind.

They think about how quickly British police identified the suspects in the London bombings last year because video cameras in the subway provided pictures.

They think about Sarasota, Fla., police arresting a murder suspect because a car-wash surveillance camera captured chilling images of him kidnapping the 11-year-old victim in 2004.

They think about the times they've walked into a deserted store parking lot after dark and felt a little safer because cameras on light poles were so obviously recording everything.

For better security, many people are willing to accept obvious cameras in public places.

But there's something creepy about being watched surreptitiously. It's even more unnerving when it occurs in a place where the person might expect a degree of privacy. For example, despite the shoplifting that occurs regularly in department-store dressing rooms, most people would object to surveillance there. Same goes for restrooms and locker rooms.

It's not clear where the line gets drawn, but the Pittsburgh Parking Authority probably crossed it when it installed hidden cameras in three of its cars used by parking-meter coin collectors. They were secretly placed there as part of an investigation of theft allegations. The authority's acting executive director, David Onorato, paid $40,000 for the surveillance, which ultimately proved the allegations false.

Mr. Onorato said, as a result, he has a "higher confidence level" in his workers. Unfortunately, it means they have less trust in him.

The authority should have given its employees the decency of prior notice. It should have told the workers that it had heard rumors of theft and intended to investigate by installing cameras.

Then, of course, the workers would have been on notice not to steal, which in itself would be a good result for the authority. In the end, the hidden cameras showed the workers weren't thieves anyway.