When you use Gnome Shell under Ubuntu or Debian, all Ms Office files are displayed thru some generic icons in Nautilus.
With the help of LibreOffice unoconv conversion tool, it is possible to use the first page of a document as a Nautilus thumbnail.
To make it even more visual, the thumbnail can be outdrawn by the document type official icon. You will then get a display much more visual.
This article explains all the steps needed to configure Nautilus to display thumbnails of Ms Office documents including document type icon and first page content, providing a simple and efficient Ms Office documents preview. It is using LibreOffice conversion tools and some very basic tools.
This procedure has been tested under Ubuntu Gnome 14.04 LTS with Libre Office 4.2 & 5.0. It should be applicable to many Gnome based distributions. It has also been tested under Lubuntu 14.04 LTS with PCManFM.