The environment I use my laptop in is pretty dusty (Afghanistan, if anyone here knows about moondust). I recently bought a cooling fan pad to help cool my laptop down when playing games, but I wonder if I'm doing more harm than good with all the extra dust being sucked into the computer. When I take the laptop off the pad, you can see dust buildup of the fan's frame.
I've heard of people using tights as cheap improve dust filters, but they're stretchy and not in nice flat sheets, so they're rather hard to work with. But it would probably be better than a tshirt (a tshirt would block a lot of air)