So what are the things you can impact in your site content that can impact search engine performance?
Hidden pages should only show up in searches IF there is a link to that hidden page on a crawled page of the site. All the pages that show up in visible navigation should be crawled, but any hidden page that is linked to from a crawled page will also be crawled.
If you never link to your hidden page, search engines should not be able to find it! This can work for or against you, but it is something to be aware of!