I have developed a web application which will conditionally show ads if the url is suffixed by a "/1". For example:
If a visitor enters the site this way, a session variable is set that will cause all pages to show these ads, even if there is no "/1" appended.
At the same time that the ads are shown, I have added this:
<meta name="robots" content="noindex, nofollow">
The goal is to not have search engines index pages with ads, so that those pages will not have a canonical problem with duplicate content.
So, my question is, is this a fool-proof way to make sure that Google, and other search engines, can never index pages that show ads, and that we will not risk duplicate content penalties?