I "Google" less and less for search results, as they become increasingly crap. They are mostly best for "big name" items; also, the prominence of StackOverflow means that some computer technology queries still work pretty well.
These days, I'm fortunate when I know specifically enough what I want that I can jump straight into Wikipedia and hopefully find an adequate page.
Whatever you are and aren't doing about it, Google, whenever I search for something detailed that's not in StackOverflow, your results are increasingly crap, once again. Pages and pages full of very spammy results.
Some time ago -- perhaps a few years ago or a bit more -- I became accustomed to fairly quickly paging several pages into the search results, where the heaviest, highly ranked spam would start to filter out and I could start to recognize more legitimate sources of information. These days... the spam results just go on and one. If there's quality somewhere in the search results, it's beyond the limit of my patience to continue paging forward and scanning.
Not that I'm using Yahoo, in preference. That part... all I can think of is measuring by byte counts, and buttloads of banner ads. Probably not the right explanation, but...
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P.S. Your (Google, again) elimination of the + operator in your search queries was, again anecdotally, another factor in the declining performance of your searches for me. Being able to tell the query engine that I definitely don't want to see results that don't include term x frequently proved quite useful. Now... the damned thing shows me "whatever it feels like", whether I quote terms, beg,.... any other suggestions?