Don't people understand that this is exactly how J. Edgar Hoover and other political thugs have concentrated their power?
Simple illustration and I'm out:
You're spotless. You work at warehouse, and you've always obeyed the law, been faithful to your wife and led an all-round honorable and upstanding life. If someone tapped your phones, they'd hear a lot of wholesome calls between you and your wife, and not much else. If they read your emails, they'd learn you have a weakness for fantasy sports and good Ebay deals. Short story: you're squeaky clean.
But is your boss clean?
You're one of two candidates being considered for promotion. The other candidate is the police chief's nephew, but he's not really half the candidate you are. You've got more experience, and you know everything there is to know about the warehouse. Your competitor, on the other hand, hardly ever seems to be around, and when he is, he's a total ignoramus. You can't fathom how he's remained employed as long as has. There's just no way he could be promoted ahead of you.
I ask again: is your boss clean?
Because as it turned out, you were passed over for promotion. The Police Chief's nephew was promoted ahead of you (and now he seems to show up less than ever). Moreover, your boss has layered additional responsibilities and duties on you to make up for what the Chief's nephew cannot or will not do. Of course, you didn't get a raise for the extra 10 hours you are putting in every week.
So yeah... If you had mind-reading powers, you'd know that your boss has been driven to near-suicide over the extortion he's being subjected to. You see, the police chief had your boss's email hacked and discovered a gay lover. Correctly, your boss assumes it'd be the end of his family if his wife found out. Suddenly, your boss found himself in the Chief's pocket, which worked out very well for the Chief's nephew, but not so well for you or your boss.
This is exactly the sort of thing that sustained J. Edgar Hoover's career.
Surveillance: it's not all about you, but it could be.
Keep this in mind the next time some idiot trots out a stupid line about "if you're not doing anything wrong, you've got nothing to hide...."