Anyone advertising with Google search ads against a single ‘exact match’ search term might expect their advert to be shown against that term, and nowhere else. If you went to the report on what search terms the advert was triggered by, you’d expect to see just one row in the table. You would be wrong. Google announced over a year ago that ‘exact’ matching was to be interpreted somewhat more loosely in future. So if you’re specifying your advert to appear against ‘blue widgets for airports’, expect to see several rows in the actual search terms report: you’ll probably see that the ad showed (and got clicks) for ‘airport blue widgets’, ‘blue widget for an airport’ and all sorts of other things.
There’s more, however. Look again at the actual search terms report, this time at the total number of impressions for those search terms. It’s not nearly as many as the total number of impressions shown in the main campaign report. This is because all you see listed in the actual search terms report are the terms which got clicks. Your ad will probably have shown for several other searches, but if they didn’t get any clicks, they probably don’t appear in the report, and remain a mystery.
It would be nice to know what these searches were. But unfortunately, until you get a click, you’re not going to find out. Google will probably argue that if there was no click, you haven’t paid anything, so it doesn’t owe you the information. I’d still like to know.