Another trick I use with Google, especially when I'm searching things that are outside of my usual interests, is clearing my cookies. Best I can tell, this makes it skip the statistical model of me that, say, suggests 'logging' is more about daemon output than about killing trees.
Now if only all the engines didn't have such a bias towards "new" material. My major search-related frustration over the last while has been how buried things become over time, especially if they share identifying lexemes with things in the news.
What's an example of a search that fails to find what you need?
Various programming questions. Don't have an example right now, sorry.
Search for programmers?
At the risk of sounding melodramatic, the internet is a great idea but the implementation sucks and there's no easy way to fix it.
Of course, one can always suggest that I am just better attuned to Google (I have Google Fu from long experience with Google and wrongfully expect DuckDuckGo Fu to be the same skill and have not developed DuckDuckGo Fu).