I got this question today from one of my collegues and needed to find the answer to it. Why did I get this question? Well one of our developper teqms provided a new solution to deploy that replaces the default master pages and the update did not show any difference after deployment. therefore we suspected that the master pages had somehow be customized which causes this behaviour.
My first hunch for finding the answer was SharePoint Designer and my favourite Microsoft Premier Support Engineer confirmed with the following article: Track Customized Master Pages
Basically you need to open the site collection using SharePoint Designer and run the Customized Pages report and apply a filter to show only the customized master pages
Below is the information that describes how to do this as grabbed from the Microsoft article
Run the Customized Pages report
For both Office SharePoint Server 2007 and Windows SharePoint Services 3.0, data for the reports generated by Microsoft Office SharePoint Designer 2007 is saved on the server on which the site is hosted. Server administrators can grant or deny access to these reports. If the reports generated come back empty, contact your server administrator for assistance. You must have at least Web Designer permissions on the server to open the site and run reports.
When you are working with an Office SharePoint Server 2007 or Windows SharePoint Services 3.0 site, you can easily use Office SharePoint Designer 2007 to run site reports that collect a variety of information about your site’s health, usage, and potential problems. To run a Customized Pages report:
- Open the Web site for which you want to run the report in Office SharePoint Designer 2007.
- On the Site menu, point to Reports, point to Shared Content, and then click Customized Pages.The report opens with all of the pages in the site listed, and the Customized column indicates whether content has been customized for that page. Note A page is considered customized only if it is included in the original site definition. New pages created from a master page, new blank ASPX pages, and custom list forms that you create are not considered customized pages.
Filter the report to show only master pages
After you run the Customized Pages report, you may want to narrow it down to include only those pages in the site that are master pages, as shown in the following illustration.
- To limit the results to master pages only, click the arrow next to the Type column heading, and then click master.
Filter the report to show only customized master pages
You can narrow the results even further to list only customized master pages, as shown in the following illustration.
- Click the arrow next to the Type column heading, and then click master.
- Click the arrow next to the Customized column heading, and then click Yes.
The report now lists only master pages that have been customized.
Note To remove any filter, click the arrow next to the column heading, and then click (All).