I recently ran across Skimmer Scanner, which is an app that uses Bluetooth to scan for, connect to, and send no-op commands to verify certain common types of card skimmers. Given that the app uses default credentials to authenticate and sends a command that does nothing but characterize the device as likely being a skimmer, would exercising this much control over an illegal/illegally installed device get someone in trouble in Tennessee? Does anything change if they are using the app as part of their work at a gas station in order to protect customers from skimmers?
The Google Play listing says
Please check your local laws before installing this product. There is implicit risk associated with publicly reporting crimes.
The describing article says
The app does not obtain or download data from a given skimmer nor does it report any information to local authorities.