URL Miscategorization for Adult Sites

Hello,

A Sophos Firewall Home User here..  I have been dealing with an issue that I am not sure how to tackle.

I want to block access to all adult sites in my network, and even though the firewall categorizes the obvious ones in the right way, there's others that are equally as harmful and they fall in other categories.  Examples:

It doesn't make sense these sites (which only allow downloading of adult content), are categorized as "Download Freeware & Shareware". I do understand it is very hard to keep up with the living internet and categorize every single site. However, this makes controlling adult content much more difficult. 

Any thoughts or ideas of what can be done here (Maybe using the Application filter based on content type?.. just thinking out loud).

So far, my only approach is to keep blacklisting domains as they popup in the log, however, this doesn't put me ahead of the game..

Thanks!