I remember seeing the Naked Rambler chap one time in the Borders , and being a bit
because a naked man with boots and a rucksack, on a freezing cold rainy day, outside Tescos, in a wee ex mining town is a bit unexpected, and hardly the romantic image of him as a free rebel striding the hills that was being portrayed
And lots of my friends were very much 'why is he being arrested? its only the human body? Hes not doing any harm'
Except in this situation Occam's Razor applies, though sadly not literally - eg the simplest explanation is better.
What are the chances this naked man walking towards me in an unexpected place is a brave soul, apparently like the Naked Rambler, making a stance against our hidebound and repressed society and its fear of nudity?
And whats the chance that its just another middle aged male who gets his jollies by exposing himself to people in non consensual situations? 
I suspect more people have experienced the latter than the former. Somehow its very hard to tell the difference when you are unwittingly and unwillingly dragged in and made part of someone else's political statement or exhibitionist fetish.
And these days of course I am usually accompanied by my preteen children.
What exactly am I going to teach them about how to react when the unexpectedly see a man exposing himself in a public place, especially if they are alone?
Should I encourage them to think hes just a harmless nudist and engage him in conversation about the philosophy apparently underlying his groundbreaking freedom from sartorial convention?
Or should I let them know in no uncertain terms this is not a situation for where they should suppress their discomfort with the situation, they should feel free to act on instinct, run, make a fuss, scream and attract attention, find another adult who could help them as statistically the person is likely to be a threat, and has already unwillingly involved them in their exhibitionism.
Again, the answer is pretty simple!