I bought a new black sleek case for my pc, to replace my old off-white budget one(still had removable side panels though) because I had 2 custom mount 120mm fans - one for side intake, one for top exhaust. This was too noisey, they had to go. Also, I had no guards, grills, or dust filters, and had the fans in there for a good 7-8 months. One of the fans was obviously sucking in - at 64cfm.
DAAAANG, it was nasty in there. So, in the middle of transfering my hardware over to this new case, I had to take some time and clean off all my boards and stuff. Inside my old case, before moving the hardware...there waws TOOONS of dust, I found LOTS of spider webs....and a dead fly! HA!
...just thought it was funny, and thought I'd share.