lucy24 - 5:50 pm on Dec 17, 2012 (gmt 0)

if it is set to "noindex" then search engine bots won't crawl it or index it

Half right. The "noindex" label means don't index. But they can only see the "noindex" (or equivalent header directive) if they do crawl.

That's why I started out asking whether it matters if people know the page exists. Knowing it's there and being able to get there are different things.