I take it you work for Google.
I have the impression that Google likes to collect data. If you are indeed interested in fixing the recent quality dip of your search product, example queries where plus (now quotes) are necessary can be automatically collected by inspecting all searches where quotes are included.
If these are too many, filter by those that had a recent similar search without quotes. I doubt this is necessary, though. Who puts quotes in their search string the first time?
If I worked at Google, I'd be interested in the growth of use of the plus-operator lately. It has become a necessity for nearly all technical searches I do. Make a chart of it. Show it to the people in charge of this recent trend. Google search has seriously gotten worse. Forcing quotes instead of plus highlights this problem because it's twice the work.