I got a failed install that is taking up some memory (god only knows where).

Apt-get clean / autoclean did not work and its not visible in the App Manager - nor does it help to reboot.

I ran apt-get automremove as root to see what it would pick up and was surprised to see apps like unrar and bzip2 - along with a lot of libs. All in all an autoremove would get me 10meg back.

What's the logic in how autoremove determines what can be removed and is it 'safe' to use?

My sample result:
/home/user # apt-get autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
bzip2 python2.5-pyinotify unrar
python2.5-gpsbt libqt4-test unzip
madplay libqt4-core libgnutls26
libboost-date-time1.34.1 libtasn1-3
pydevicemanager libgcrypt11
libboost-iostreams1.34.1 libvorbisidec1
libflac8 libgpg-error0 python-dateutil
libssl0.9.7 libboost-filesystem1.34.1
libid3tag0 pygtkeasyapp ttf-droid
The following packages will be REMOVED:
bzip2 libboost-date-time1.34.1
libboost-filesystem1.34.1
libboost-iostreams1.34.1 libflac8
libgcrypt11 libgnutls26 libgpg-error0
libid3tag0 libqt4-core libqt4-test
libssl0.9.7 libtasn1-3 libvorbisidec1
madplay pydevicemanager pygtkeasyapp
python-dateutil python2.5-gpsbt
python2.5-pyinotify ttf-droid unrar
unzip
0 upgraded, 0 newly installed, 23 to remove and 20 not upgraded.
Need to get 0B of archives.
After unpacking 10.8MB disk space will be freed.
Do you want to continue [Y/n]? n

EDIT: This got posted in the Maemo5 category by mistake.
The device this was run on was an N810 running Diablo.