You know, personally, I believe that people are entitled to their privacy.
For example, Paparazzi are basically exempt from stalker laws and can get away with anything except murder and trespassing. However, I don’t agree with that because of their, often, Herculean efforts to obtain salacious/sensational photographs.
Speaking of “prey”… it should be illegal to hunt/chase down a celebrity… who has vacated to their private island in the Pacific… to relax away from intrusion/prying eyes… to be dogged by paparazzi in helicopters…with long lenses… photographing them naked on their private beach.
It is trespassing and a disgusting practice and as far as I’m concerned does not factor into “freedom of the press”. It’s an man-hunt! Freedom for whom?! More like “free for all”. If the paparazzi did the very same thing to anyone else they’d be arrested for stalking. Celebrity or not it’s unfair and should be illegal. Bella’s Law, lol. 
No, no one is expecting to be under surveillance unless it has to do with security/protection. And with the establishment owners consent. A bank, the entrance of a hotel, government buildings, traffic intersections in some cases, etc. Security/protection. Put yourself in your “subjects” shoes and think about how you would feel if someone was spycamming your ass.
If I owned a convenience store or a bar, I would be disturbed/angry to find out someone had been video-recording my patrons and would take whatever steps necessary to stop it. It’s not illegal, huh? Well, there are things that can be done to stop it that also aren’t illegal.
Although, I am not above using illegal tactics to rid my premises of vermin, need be… cough… go ahead, tell my mom, lol.
If nothing else it’s testimony to the true character of the individual who does this to others, and for whatever reason they use to justify such action. Big time beta-behavior if ever there was. 
There are plenty of “expert” videos/books on how to read/learn body language but they won’t really do you much good unless you saddle up and stop dicking around! Grow a pair and get your ass in the game instead of “spying” from the sidelines! 
Bella