Hi,
i cannot help you with the searches, as I did not try anything like that yet.
BUT: If you just want to skip one "admin" folder (subtree), you might want to solve this easier and more secure with sections.
When "admin" is some area, which should only be usable by "admins", you could try this (we use this setup):
Create a section ("Admin-Area"). Assign this section to your admin folder, which will assign it recursivly to everything inside.
Then change the "Anonymous" role, so that your users cannot read the content. Usually, Anonymous can read all sections, which you do not want.
Create another role called "Admins" (maybe there is one already) and allow the to read/create/edit/delete everything inside all sections. If you have to create the role, assign it to your "Administrator Users" group.
This is a rough solution and may be refined more, if you have more more user groups. Note: Always remember to STORE the new role policies!
This should give you, what you need, is very elegant, uses ezPublish permission system and does not require ANY coding.