CCleaner?

I'm coming around to this point of view as well. So much of the cleaning is habit due to watching performance improve in XP after cleaning, then extrapolating that to confidence that finding all of the registry shells in Win7 after uninstalls is doing something important.

Maybe not. I'm not in as much of a hurry any longer to use CCleaner or boot-time defrag, even though that last has sped up boot times by as much as a minute in a few cases so again seems convincing.

Tinkering may indeed be an ancient profession. A perfect Win7 install on adequate hardware seems to trump all that. But is proactively cleaning a Best Practice?

I would like to add that if you are going to use ccleaner, you could get the best out of it by adding something called CCEnhancer - SingularLabs
It adds support for many programs to ccleaner to help clean their left over junk. I think the two make a great addition to any Windows system.