when I reached the highest level of espionage it said I had "Spent trillions to get there". Is that misleading?
I used the agents who were sitting around in my pool anyway and as far as I know there is no support cost for agents or doing system wide surveillance?
This is probably left over from DL, where you spent money per week rather than agents to gain intelligence on an enemy. You are correct, and with the addition of the civ-wide remove buttons, the text is no longer technically necessarily true (although it may be in some instances-after all, a trillion is only 1,000BC).