If you have a lot of user IDs on your AS/400 you might find this tip helpful. The idea is to copy user information to a DB-file and to query this file, e.g. by importing it to a spreadsheet, and turn and twist the information in order to find strange things etc.
The command is: DSPUSRPRF USRPRF(*ALL) OUTPUT(*OUTFILE) OUTFILE(MYLIB/MYFILE)
Check it out! You'll be amazed what strange things you can find among your user IDs.