Yep, second that again and again. You will be amazed at what you will find in there. You think you have a sort of clean house, hah!!! Try living with an asthmatic with serious allergies, then you start to think clean, really clean.
They really should equip these things with filters on the cooling air intakes. It would eliminate 90% of the problems people have with BSODs and unexpected shutdowns and crashes and poor performance. It would be so easy to do too. Plus they should make getting to the fans and heat sinks much simpler. Better yet go for passive systems with heatpipes and large fin arrays, perhaps on the back of the lid. Even if the fins were only 1/4" high, spaced at 1/8" you'd get close to 600 square inches of dissappation, less than 0.1 W/SI. With a folded enclosed setup, you could double that and with a small fan on a manifold, triple the performance of that. And yes, there are heatpipe hinges. Well, as stuff gets smaller and smaller and more and more powerful, this type of stuff will start showing up.