Are you planning to do this on principle, or do you know you actually have a problem?
Consider the damage that might be done opening the thing up for cleaning (check iFixit for the various cautions that accompany the repair procedures) and balance those risks against the possible benefits of cleaning out some dust.
I wouldn't bother unless you know there is a problem. Unless you live in a terribly dusty environment I doubt you'll find enough to clean that justifies opening it in the first place. Plus he fact you even want to clean it makes me think your house/room stays fairly clean anyway again reducing the need to clean it.
If you do open it though I would make it worth your while and upgrade something. While I'm sure its fine, you could consider applying a really high quality thermal paste.