Same problem with Google; most of the search results are from very old topics. Some expert members helped us with tools to make the process as easy as possible (loyce,tryninja), but unfortunately most users don't know about them and not everyone who knows about these tools can use them. It would have been better if the feature worked better on the forum, and let's hope that we won't find these problems in the new version of the forum software.
I do a specific keyword search with quotes and prefix it with site:bitcointalk.org. You can check this reply to learn how effectively to use Google or any other search engine to find threads in the forum. https://bitcointalksearch.org/topic/m.64643312
The only downside is that you should know what you want to search in the form of a title or keyword. It takes time if you do not know the right title or the specific keyword.
