How to create a view returning untranslated entities
I do not think you can filter for untranslated nodes. It is not exactly what you are asking but the way I did it is this:
1. Create a Content View
2. Add the field which can be translated (e.g. Body)
3. Add the field "Entity translation: Body: translated"
4. Choose one language of the translation (e.g. Current User's Language)
5. Click "Rewrite the output of this field" and type "X" in the Text box
6. Click "No results behaviour" and type "-" in the Text box
7. Repeat steps 3 to 6 for other languages if you want to check multiple  

This should produce a table with the first column being the source language and the rest of the columns corresponding to the different languages of the translations. When a record has been translated an X will appear, otherwise a - will appear.