Not "clean install"
The term "clean install" refers to OS 9 and before. It was a clean installation, a new "System Folder", not a wipe. A wipe is a "clean erase". The equivalent of "clean install" in OS 10.5.8 and before is the option "Archive and Install". The archive is the old system, the install is the new system. The two (old and new) are totally separated, thus the new install is clean, a clean install. With OS 10.6, a direct reinstall will automatically put the old system into an archive.
The big glitch with the 10.6 reinstall is that it fails to handle an archive of the Users. Instead, it changes the status of all previous user accounts to standard accounts and upon restart, the Setup Assistant directs you through creating a fresh account -- that may or may not be an admin account.
The surest way to get a proper clean install (as opposed to clean erase) out of OS 10.6 is to complete the reinstall, complete the new user, boot to single user mode, rm the local.nidb, mv the old "Users" directory to "Users-old", rm the .applesetupdone file, reboot, create a real admin account (best to use the same full name and shortname as your original account), and Bob's your uncle. Then you can create new admin users to match any other old users you may have had. Mucking about to move stuff from the old to new users should not cause any permissions miss-match if they have the same short names.
The purpose of a clean install in OS 9 and before was to solve OS install issues, not to solve HDD file system errors. Archive and Install also has the purpose of solving OS install issues.
Anyone who was using computers when Apple introduced this feature (System 7.5) knew that it was hidden then and you had to hold Command-Shift-K to get the options window to appear. Starting with OS 7.6, the installer showed an "Options" button to bring up that pop-up screen with a check box for "Create New System Folder (Clean Installation)".
I have no idea why the PC geeks usurped this phrase and decided it required a format. Format is to remove a corrupt file system, not needed to clean install a fresh OS. Anyone who erases a HDD when there are no errors found by Disk Utility, Drive Genius, TechTool Pro, Disk Warrior and the like must have a phobia. Just go really overboard and replace the whole HDD. Probably has problems that even an erase missed. Toss it.
http://support.apple.com/kb/TA38095