| Beware with deborphan – it relies on dpkg/apt database of dependencies (which happens to be the correct thing to do).
But dpkg/apt only records what you have installed using the package management system. As a result, it doesn’t take /usr/local into account. So whatever libraries you installed to satisfy some software of your own (/usr/local/whatever) might be considered redundant.
Apart from that, deborphan rocks 🙂