Confirm the summary page, the files page, and the download page for project 3 have no ads - you'll have to view source to verify no ad JS is present. The files and summary pages would normally have ads inside the #sidebar div. The downloads page's entire content is ads so it should just be the header and footer.
Browse to /projects/project1
Confirm the same three pages for this project do have ad calls.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
sfpy:ka/1800
To QA...
$ mongo gutenberg
> db.global_settings.update({}, { $set: {'no_ads_projects':['project3']}})
/projects/project3
/projects/project1
Also verify that no 'COMSCORE is not defined' JS errors occur on any of the pages.