Yea...Dust is not the only problem.

Anything small enough that can be picked up by moving air is bad. On one call I had to go out to the customer site and troubleshoot his desktop computer. His computer was locking up. I usually check the basic things first. So I unplugged the power cord and opened up the computer side panel. I found the CPU fan and the system fan was caked with carpet fibers. He had moved into his new house about a month ago and the computer was sitting on the brand new shaggy carpeted floor and the fans were sucking in the fibers. So I took the computer outside and blew out the fibers with canned air. It took two cans!

If possible, always keep your computer off the floor. Put it on a stand if you don't have a desk with a shelf for the computer. The floor catches everything and if your computer is sitting on it, it will suck in whatever it can.