Comment 67 for bug 295536

This worked for me:
Say you want the PDF output in: ~/pdfout123

1. mkdir ~/pdfout123
2. go root with sudo su
3. change the out-line in /etc/cups/cups-pdf.conf to: Out ${HOME}/pdfout123
4. change the two lines in /etc/apparmor.d/usr.sbin.cupsd to: @{HOME}/pdfout123/ rw, and @{HOME}/pdfout123/* rw, respectively. (mind the space before rw and the comma after it)
4a. do *not* backup usr.sbin.cupsd to a file in the same dir because apparmor iterates over the files and will try
to load them all, including any .bliep.blap.blop.backup files !
5. /etc/init.d/apparmor stop
6. /etc/init.d/apparmor start
6a. ** restart won't work and restart will also not complain about duplicate files loaded, so stop and then start apparmor.
7. /etc/init.d/cups restart

Now try to print someting to the PDF-printer and it should appear in ~/pdfout123
If it does not, try a reboot. (My deepest aplogies to any Debian readers...)
If it then still does not work for you I guess I was just lucky.

FWIW:
I changed *no settings* on the /usr/lib/cups/... dirs as those are correct by default.
The first culprit is that ~/PDF is often not present.
The the second culprit is that the output-dir has to be specified in *two* /etc/config-files.
The third culprit is that apparmor does not correctly reloads changes by a simple restart.

Access on my ~/pdfout123 is: 755 (did not try other settings but logic suggests 700 should work too.

I hope this works as good for you as it did for me,
Cheers,
  Interbird.