Apt-get clean and apt-get autoclean clear the cache not installed
redundant files. With debian there is a utility called dselect but it is
still not as good as aptitude. Thing is while aptitude is a text
interface it does provide more info and remove redundant files which the
others don't do. I just use aptitude in the command line e.g. sudo
aptitude install 'program'. I think the reason more people don't use it
is that they have used debian and so stick with apt-get.

I look up apps in Add/Remove or synaptic but always install with
aptitude and i've noticed the difference. In the ubuntu documentation
somewhere there is a doc called Apt-get v Aptitude which you may enjoy
reading.