If this is causing dust to accumulate on exposed circuit components, then you have an undesirable situation.
I have written acceptance test software for Seagate. As of three years ago, one of their acceptance tests consisted of injecting air into the drive and verifying that the pressure did not drop over a fixed period of time. In short, these were units that were sealed and, for all practical purposes, impervious to the entrance of dust.
I am unable to address this issue for units other than the Seagate drives, though I would suspect that those produced by other manufacturers would be similar.
Indirectly you are raising a very interesting question for the overclockers. They may install the latest WhizBang Model 1099 heatsink and fan units to keep their CPU temps down. Dust accumulations may change their effectiveness over time and the owner never know it until after his CPU has lunched out. This would be a problem of course only for those who do not actively monitor their CPU temperature on an ongoing basis.