As of the next release, DiskPaths will skip unassigned disks (e.g. disks left over after an aggregate has been destroyed) since it is not its job to identify them. Skipped disks can be viewed with -verbose.
From now on it is important to configure Disk Check with -what=unassigned. A best practice is not to leave any disks unassigned (thank you to Walter RING of NetApp Austria for his insight!)