Obviously, it is a good idea to close the curtains before getting naked these days, whether at home or a hotel or wherever. Morality police are lurking, armed with camera phones.
From what I gather, courts say no expectation of privacy if one can be seen from a public location. I am not sure if the use of binoculars, telescopes, telephoto lenses, digital zoom, etc. negates that. Not that it matters. This guy lost 6 months of his life over pretty much nothing. At least he had a good lawyer and got some money.