Comment 8 for bug 162426

I found a good example of how I would expect the mrtg package to behave, in this instance it's the openvpn package. I had the package already installed so I just added another file to the conf directory to emulate the presence of user data. I then purged the package. You can see at the end of the listing that the user data is left untouched and the directory intact.

elliotp@lenny:/etc/openvpn$ ls
update-resolv-conf
elliotp@lenny:/etc/openvpn$ sudo touch testing
[sudo] password for elliotp:
elliotp@lenny:/etc/openvpn$ cd ..
elliotp@lenny:/etc$ sudo apt-get --purge remove openvpn
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED
  network-manager-openvpn* openvpn*
0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded.
Need to get 0B of archives.
After unpacking 1581kB disk space will be freed.
Do you want to continue [Y/n]?
(Reading database ... 132272 files and directories currently installed.)
Removing network-manager-openvpn ...
Purging configuration files for network-manager-openvpn ...
Removing openvpn ...
Stopping virtual private network daemon:.
Purging configuration files for openvpn ...
dpkg - warning: while removing openvpn, directory `/etc/openvpn' not empty so not removed.
elliotp@lenny:/etc$