When looking at new questions, I want to filter out questions that are tagged for subjects I don't know enough of or am not interested in.
When I'm searching for information, I don't really care about filtering out these tags as answers which may be filtered out may still be relevant and provide an answer.
For instance, someone may ask about a tool to help them perform screen scrapes for java apps. They may be developing in C++, and so tag their question with this. An acceptable answer may include the Java Access Bridge, which can be used from any .NET application via p/invoke. While I filter out C++ questions, when searching for ways to scrape Java apps this workable answer would be excluded from the search results.
Currently, I'll search for an answer and I'll see lots of results pop up and then immediately disappear, being filtered out. The only way to stop this is to reload and stop page execution before the filter runs. Its a hit or miss situation.
My suggestion would be to provide a "Filter search results" checkbox on the screen or let me set this from within my preferences.