Building Bluehood, a Bluetooth scanner, reveals how always-on Bluetooth broadcasts personal data. The project, developed by a privacy advocate, passively scans BLE signals to detect nearby devices like phones, wearables, and vehicles. It highlights vulnerabilities like the recent WhisperPair flaw affecting millions of audio devices, showing Bluetooth isn't harmless.

The author found patterns revealing delivery schedules and neighbor routines, proving even passive scanning leaks significant information. Bluehood's web dashboard tracks device presence and correlations, demonstrating how easily personal habits become exposed.