just like the author claims that we do not appreciate the good consequences of surveillance because, when it works well, it's invisible, i can claim the same about it's negative consequences. e.g., if congressmen and -women are changing their votes on intelligence budgets because some spy found out they hired a prostitute some time ago and blackmailed them. indeed, when it works well, it is invisible.

the core of the issue is limiting the spy's power, and giving them appropriate oversight.