You are correct and I think in Lane County we have our own definition.  As I recall, back in the 70's or 80's Jerry Rust and the County Commissioners (maybe only three back then) had hearings on public nudity and decided that it should not be a crime unless the purpose of being naked was to arouse oneself or another.  It passed and no one really made a scene over it.  Later we had nude recreation areas with the last major one being closed off by land by Lane County.  But these two weirdos were probably wasted high on meth and thought about one thing only and made sure that other people were thinking about that same one thing as well.  It doesn't make for a good ending.  Sick and wrong apply to the definitions here and all the signs point to a really good batch of meth that makes you want to let your hair (or pants) down.