Medjai can't stand the foam beds either. He also likes to eat the thick parts of any blankets that have thickly stitched corners. I don't know what it is about those things, but Medjai is perfectly fine with his polyfil bed. He also did ok, when i got poly to fill over the foam of one of those taller sided beds. Medjai also has to get out anything out of the ordinary on the toys. Any stuffed toys are IMMEDIATELY relieved of their tags, strings, and any thickly filled parts.
I just associated it with a natural desire to even everything out. I'm a psych student, so I just related it to human disorders like OCD, where people have to have everything just perfect. I'm kind of like that sometimes, so it was easy to assume my dog might be.