Hidden cameras are being found in hotel rooms, house rentals, cruise ships, and even airplane bathrooms, leaving many travelers to wonder: “Could a hidden camera be watching me?” Spycams, as they’re called, are getting smaller, harder to find and easier to buy. From alarm clocks to air fresheners, water bottles and toothbrush holders, cameras come embedded in common household items that seamlessly blend with home decor. They can be purchased in shops or online, and through retailers like Amazon and Walmart. And rather than having to retrieve the camera to obtain the recording, owners can stream live images straight to...