What I do is create a specific profile for the type of category I want to watch. For example, create a profile with only porn selected as the denied rule. When you create a profile, it will have a name like "content#" (content1, content2 ...).
Then go to the "Logs" area and open up the "Content Filter" log. In the top left there is a "Filter:" input field. Type in the name of the profile you want to watch. For example, if the porn profile was called "content3", type "content3" into the "Filter:" input on the log page.
This will only show hits for that profile. Obviously this isn't the best way of doing things, but its a great way to drill down on specific categories you want to keep an eye on.
Hope that wasn't too confusing...