I think in most cases, formatting is the "lazy" option, but I wouldn't dismiss it as "never an option" or "never the right option" because there are cases were, for multiple reasons, you might as well.
For me, it isn't so much an issue of being lazy as it is of being safe. If the machine is of any importance, a format and re-install is the only way I will ever trust that machine again. You never know what you could have missed, or something so new that automatic scanners don't catch, etc.
Obviously, if the machine is Joe Schmoe's ebay machine, then you have a different story completely. :)
Greg
