There are some interaction/consistency problems with the permissions. I have tested these on resources and announcements, they may also apply in other places.
1) When 'Revise' is unchecked, and 'Delete' is checked, the user cannot revise or delete, which makes sense. However, there is no indication of this in the permissions screen, where delete should be grayed out in this case. The user can also still see the delete button in the page when their permissions are set this way, even though the permissions prevent them from actually deleting things. The ideal solution would be to hide the delete button in the interface ANY time the revise button is hidden, in addition to graying out the delete permission check box as described above. This would also solve the following problem.
2) In the case where 'Revise' is turned off but 'Delete' is turned on, there is different behavior in different tools. In Resources, it gives you an error and leaves you at the delete confirmation page. You then have to hit 'Cancel' to return to the regular Resources page. In Announcements, you get no error message, and you are automatically returned to the Announcements page, where the item you tried to delete is still visible. The Announcements page should act like the Resources page.