I recently bought an external USB harddrive, made by Toshiba. It's the HDDR500E03X model with 500GB space, internal shock sensor and ramp loading technology. Now yesterday I learned, that I can also cover its health status using the smartmontools. The usb* device types did not fit, but the sat did. It is as easy as running:
smartctl -d sat -c /dev/sdb smartctl -d sat -t long /dev/sdb