I think the reason so many are out there on the map has to do with some pin assigned to a region and the campaign is more of a national campaign than at a single address, so like the previous reply said, you can choose any one really. It seems to be a limitation of Presto where a user would think the map can only show single locations since mystery shops usually are for that, but when its a national campaign, the question is how do you represent that on the map? I think each pin maybe shows a zip code or some imaginart geo-center of a city.
I've seen this too with things like casino apps where you can be a member of a state, but you see the pins everywhere around the state. Same for some food or beverage delivery apps. I wish there was a way to filter out more than one keyword so the pins disappear and the map doesn't look so cluttered.