I know there seems to be quite a few other posts regarding this, but never seen a definitive answer.
Regardless whether the "use thumbnail as only image" is checked or not - no "attached image" is passed through to facebook...
Looking into the html, og:image tag is added twice into the header - once with the correct attached image url, then again with the wordbooker-blank image.
Feel free to check the site and view the source here: http://www.wildchildmedia.co.uk/2012/03/super-stylish-2d-handbag/
and the result from wordbooker here:
Any help to get the thumbnails/attached images to work every time would be awesome!!