You vote for a site and give it a rating according to what you think of it, e.g. click the webrep image on the page. This opens up the WebRep voting window, the slider at the top of the window can be clicked On Red or Green or varying shades in between.
Now you can also select what you think the content of the site is.
Now that is able to reflect a negative opinion of the site, see image example of the avast forum, Good rating based on many votes and a content of IT/Download, the nearest to the Forum being IT related.