I just had the unpleasant surprise today to see the file-roller could not open a zip file. So I run file file_name.zip and it says it's 7zip archive. I change the extension of the file to 7z and behold, file roller can now open the file just fine.

Is there a way to make this utility smarter? 

Example: If I change the extension of a png file to jpg or gif, the utility the opens it does not care about the extension at all. The file will still display just fine(GIMP, Inkscape, Shotwell)*.

* unless it's the GNOME image viewer which is just as bad as file roller. It even tells me it's not a gif or jpeg file and shows the first part of the magic number but it can't figure by itself the correct image format. I need to file a new bug for this one :/