if you want more accurate search results I guess you should focus on a specific board.
like you are looking for information about futures trading. You can first go to the trading board, and only then enter your keywords. so the results you will get will be according to the trading board.
It's only give you less accuracy or even zero since the forum search engine is suck.
You can't really expect the topic you're want to get is posted in appropriate board since some discussion could fit to 2-3 boards, it just depend on the moderator who move it/or the poster is.
Example you want to search about 1xbit scam, scam accusations would be a good section to get it. But if you search on 1xbit official ANN, you will find a lot complaints too that you don't find it on accusations board.