TI, I mean that a few years ago, before the rise of paid advertising (and before Google came around), most searchers were educated (probably on Alta Vista) to type in things like "blue widgets for sale in london" whereas now a lot of the transaction occur when someone searches for "blue widgets" or even just "widgets". It's because the searchers are new, or lazy or both.
So true, I am sure some of them even type the word "blue" in the hope of getting their desired result.
There is the somewhat weird belief that your PC and favourite search engine KNOWS what you want :)
maybe a sign of things to come, personalised search.
until then I am with Webdiversity on this 1, go for more exact matches and less negatives.