As far as voyeurism goes, I know most people these days have a strict "consent only" policy. Call me a villain if you must, but I believe "least harm" is a better rule. Certainly, as long as these things are considered taboo, a pervert's going to have to reach a little bit in pursuit of his happiness. If you want to improve shady behaviors, you have to stop demonizing the desires that lead to them in the first place. Empathetic redirection is superior to an "exterminate the pests" approach.
[description: a naked man with erection hides in the bushes next to a girl sun tanning in a bikini]
Anyway, if you manage to get a peek at something, what you do with that view is what matters. If you call the cops and complain (about something harmless like getting dressed in front of a window), then you're being a pest. If you use that information to harm the person in any way - e.g., spreading rumors, damaging their reputation - then you're also being a pest. Certainly, if you're trespassing in any form, then you're not just being a pest, but a criminal, too.
But if you just enjoy the view and then go on your way, there's no harm done. Erotic appreciation is far from the worst thing anyone can do to another person - that belief is symptomatic of a sex-negative perspective, in which sexuality at its base is this violative, corruptive influence, instead of a positive background energy that imbues most of our interactions in life.
