That is a good idea. However in an environment with multiple persons delegated to create guestpasses it might not work (usually they omit the comment field).
An alternative, given to us by support, is to enable the Web Authentication Debug Component (from web UI Administer-> Diagnostics) and retrieve the password from the log:
Oct 10 17:37:47 IP ZD syslog: handleRequest():handling CreateGuestPass from IP(of the guest manager)
Oct 10 17:37:47 IP ZD syslog: setSessionVar():sending session vars gentype:single
Oct 10 17:37:47 IP ZD syslog: setSessionVar():sending session vars fullname:Conference
Oct 10 17:37:47 IP ZD syslog: setSessionVar():sending session vars key:password
Oct 10 17:37:47 IP ZD syslog: setSessionVar():sending session vars wlan:guestSSID
Oct 10 17:37:47 IP ZD syslog: setSessionVar():sending session vars starttime:
Oct 10 17:37:47 IP ZD syslog: setSessionVar():sending session vars expiretime:
The fullname:Conference and key:password are the needed information.
However enabling this debug component leads to an increase of ZD CPU utilization and memory.
We only used it temporarily, since we had to split the total number of APs between two ZDs and needed to syncronize the guestpasses which were created on only one ZD by the guest-managers.
An alternative is, of course, to create a new guestpass in case the password was lost.