If you delete a file that was indexed by Ubuntu and delete it via Nautilus, it will not show on Dash anymore. However, if you search for it, its parent folder will show in the search results. This is misleading for the user and might be a problem for sensitive information (a person searching for something in the computer will know that a file with those keywords in its name has been there, even though the file doesn't exist anymore)
If you delete a file that was indexed by Ubuntu and delete it via Nautilus, it will not show on Dash anymore. However, if you search for it, its parent folder will show in the search results. This is misleading for the user and might be a problem for sensitive information (a person searching for something in the computer will know that a file with those keywords in its name has been there, even though the file doesn't exist anymore)