Cloth produced in Silesia was once renowned for its high quality. Unfortunately, textile makers elsewhere began making cheap imitations, passing them off as Silesian. Forgeries became so plentiful that people began questioning anything said to have originated there, thinking it of dubious authenticity and quality. A slip of the tongue or two, and things Silesian became just so much sleaze.
Sleaze effectively obscures the real issues in the news, but for creating out-and-out fabrications, nothing covers up better than bombast — thanks to the Greek bombyx, the "silkworm" who wove the Old French bombace, the cotton-wool used for padding in garments.
As bombast once made it difficult to see the real contours of a garment, it now rounds out and gives arguments shape, making them appear fuller than they really are. It also helps us bamboozle others — to "cheat," or "practice deception," just as merchants once innocently stuffed shirts with paper to fill them out for display.
Currently, stuffed shirts (19thC.) are those with an exaggerated sense of self-importance — the source of many of our fabrications and the originators of much of the sleaze.