I've seen the spoiler formatting used on other sites where, say, they discuss plot elements of movies and people don't want to give away a key element to someone who hasn't seen the movie and is browsing casually.
It looks like this and requires that you explicitly choose to see the text by click on the "Reveal spoiler" button.
I didn't realize that this was implemented by a generic feature of the markup that is, apparently, available on other sites. I just saw it used in the answer to a homework question here, so I'm wondering what people think about its appropriate use, if any, on physics.
Example answer here: Electric field due to line of charge: A special case
Once seen, I wonder if people will try it more. I'm inclined to think it should be discouraged because I cannot see where it would be legitimately used. Thoughts?