any eh!
Not sure I'd claim ANY, but probably 99.9%
Without using a protocol sniffer I did run into one that was pretty darn close to impossible to grab their stuff.
Don't recall the site - was a while ago and just some fluke site I happened upon.
Overall though I agree - nearly impossible to stop someone from taking your content. Heck if worse comes to worse they can always do a screen cap and make the image.
