I'm going to pick on Apple for this one, but it happens all over the web. Lets say you're trying to view a web page and for whatever reason, it's unavailable. Perhaps there is a server error, or perhaps there is scheduled downtime, or the site has been taken offline. So instead of seeing the page you were trying to view, you see a "Try again later" page. Okay.
Time passes. You try again. Still down. So you wait some more and try again. Still down. You may be viewing a page such as this one. Note the address:
Clicking the refresh button in your browser should cause that original page to reload. But when a web site does this to you, it never will. Because you're not reloading the page you were trying to view— you're reloading their "We'll be back soon." page, which will never change.
This is broken. There is no good reason for redirecting a user's request in this way. If you're doing this to your users, please stop doing that.