I just noticed a lot of page titles in Google Analytics that start with “Page Not Found”. I investigated for a while and it turns out that they are private forum topics that are sending 403 status codes to search engines.
I think that those pages should have a different page title so they don’t show up in analytics when people search for URLs that have the title “Page Not Found”. The pages were found, but the visitor just needs to log in.
The message on the pages themselves says: “Oops! That page is private.”
I think something like “Please log in to view this page” would be a better <title> for those pages when the settings allow anonymous visitors to see that private pages do exist.