All well brought-up dogs (and I like to think that ours are so), know quite well that there are two classes of things in the world: things Dog is allowed to chew and things Dog is not allowed to chew.
The first category is usually fairly limited and includes designated "chew toys," Nylar bones, tug-of-war ropes, some treats, etc. The second category of forbidden items includes all the rest of the world, but especially blankets, pillows, dog beds, shoes, clothing, TV remotes, glasses, and many truly fascinating things. Many are all the more desirable because they hold the scent of beloved Human.
As indicated previously the well brought-up Dog knows that he is not suppose to chew these wonderful things. However, dogs are very philosophical beings, and they have developed a marvelous philosophical concept of "attachment." The basic axiom of attachment philosophy is that any item that becomes attached to an allowed chew item, automatically may itself be chewed.
Suppose for example, that Dog's favorite and well-chewed Nylar bone becomes entangled in the blanket on the bed. It is not Dog's fault that the blanket is attached, no indeed. What other choice does Dog have but to chew the blanket in order to exercise his legitimate right to chew bone? None of course.