Unless I'm worried about search engines (e.g. public websites), I don't bother at all. A warning on the screen would be good manners, if you have the time to spare...
Most common users will not disable JS (at least not on purpose), and "super users" should know better. There are better ways to stay safe/anonymous on the internet.
This is only my personal opinion, of course. I'm not the type of person that likes to please everyone at the cost of my own "blood". Vast majority is fine by me :p