I know Google started deteriorating. It was in 2008 or 2009. Up until then Google would return 0 results if it couldn't find a document with all the words you specified.

Then it started serving synonyms, attempted to correct spelling, and so forth. Instead of serving up that there was 0 results, it attempted to be "helpful".

For a while, you could enable "verbatim" search, but even that has gotten corrupted.

Their search quality has deteriorated ever since that change. It is sad.