4 Answers

Yes, scanning millions of conversations for key words is not difficult. When you use google you are using a search engine to find instances of the key words in a prioritized data base. This technique is like dumping gravel onto a screen that has holes of a specific size and shape. The stones that pass though the screen are what you want and all the smaller stones also. a second screen that passes everything smaller than  the size you are looking for reduces the number of stones closer to the size you want. Since this process can be done electronically then every conversation and stream of data in the world can be filtered for that keyword in every language. There are no secrets on the net. The problem is that there are lots of hits on key words from many different sources. Repeating hit sources show a higher activity level for the keyword suggesting some targeted activity. So now we know that 40% of the on-line sales of Pampers was in the 11 western states of the US.