I don't know if they still do this, but MyBook* used to use encryption on their interface, preventing use of the drives outside the enclosure. Not an issue if you're planning to format the drive outside the enclosure.
That didn't prevent you from USING the disk, but it would just prevent you from using the encrypted data via the enclosure - without the enclosure. The disks themselves were perfectly normal, even regularly branded (green or even red) at the time.