When i am searching for some not well know item (being intensionally not disclosing name of it) but really important for my cause, it is being not found in the top ten results while i am searching it on the Google. Which makes me fade up.
Search engines list things on top search results lists only based on trends in search. Most people keep their searches as specific as possible. As a result abscure terms are not frequently searched for and by the same token not listed in top results. That means the algorithm is good in sensitivity and specificity.