I imagine fabric would act somewhat as a moisture buffer, but I doubt it would help too much with fogging windows. The issue is that when you breath, you breath out moisture. That moisture has to stay in vapor in the air, and as your air cools it can hold less and less moisture. If the air is approaching its dew-point, the excess moisture will condense on the coldest places - which is usually the window. I can't imagine the fabric would collect moisture fast enough to keep it from condensing. Of course this is all just my opinion - I have never tried it.