Ah, your thinking of this scenario.
directory /foo with permissions something like drwx--x--x
containing a file quux with permissions like -rw-rw-rw-
In this case you cannot do an ls of foo if you do not own it. (If the x's weren't there you couldn't even cd into it). But if you know quux is there you could delete it by specifying the complete name:
You can also read and edit it as long as you specify the complete name. It is actually wise to change the permissions of your home directory to something like this if you are on a shared system.
I can explain why the other thing won't work but it is very geeky... in short everything in *nix is a file... absolutelly eveything, without exception! Except directories.
In many ways they act like files but they are not. Yep, your sound card doesn't have an inode but it is a file. Each directory does have an inode but it isn't a file. It is one of the unix paradoxes... but is essential to ensure the stability of the system.
No one, not even root, can write into a directory. Even if they have write permissions. All changes to directories are done through system calls which perform their own permission and sanity checking. This is why you can't rmdir a directory with something in it (the system call fails).
Even if you could find a way to delete/edit the directory (like umounting the disk, finding the entry, and editing it by hand. The files will still be there. When you next run fsck (which will probably happen soon after you mount the disks and your kernel panics because the file system isn't consistent)... it will discover inodes which are not associated with any directory entry and create an entry for them in /lost+found (at the root mount point for the device /usr/lost+found whatever). These files will retain the original permissions, owner, etc. Only the name and path will be lost.
So, even if you managed to mangle to writable directory the files would be fine... just moved. Aint un*x/linux cool.