I'm fed up with the sensationalized stories from http://www.dailymail.co.uk and would like it not to appear in my news search results. I found a way to eliminate it from the news.google.com aggregation when I'm logged into my Google account.
However, if I search for topics in the News section, that site shows up in the results. I realize I can do a
-site:dailymail.co.uk, but I tried adding it to blocked sites in general search preferences (requires login to Google), but that didn't work.
Here's a related question that implies blocking sites doesn't always work.