Recently, I came across an issue in SharePoint 2013.
If you name your page (eg. a publishing page) something ending with “default.aspx”, search will not show this page in any search result. But there will be no errors in the search index log and you will be able to find the page in the search index. It will just never show up in any result.
I think Microsoft implemented a filter for default pages of webs by just checking if the file name contains “default.aspx”.