Are cheap Amazon OBD2 scanners safe to leave plugged in?

Long-term users on r/MechanicAdvice report leaving BlueDriver and Veepeak dongles plugged in for years without battery drain issues, but cheap no-name dongles are a common cause of parasitic draw. If you plan to leave one in, stick to a known brand and unplug it if the car will sit for more than a few days.