I can prove to a handful of people but I'd never care to prove it to the world... not even to my neighbors, for that matter
Astral spying? I don't think so.
So here's the thing: if you do something in the physical layer there are no immediate consequences. For example, if you start thinking about killing someone, nothing happens, they are just thoughts
But the spiritual layer is not cartesian and there, if you start thinking about killing, I'll be joined by many other like-minded. Everyone around the "murder" egregora will be attracted to you.
So, yes, you can spy and e an Astral Perv, but you'll attract dense vibrations to yourself and that will significantly make you less conscience, making the Projection foggy and leaving you with a blurred memory (opposite of the vivid memory and clear projection you have when the vibration is subtle, further away from the dense matter (like an atom, in a way)