I used to control certain hits not being logged by Apache by the use of the "dontlog" environment variable -- example:
SetEnvIFNoCase User-Agent "Googlebot" dontlog
These used to work flawlessly but I noticed sometime, probably in the last couple of months, they've ceased working. My config hasn't changed so I guess it's Dreamhost's webserver (or on my machine). I'm on sawtelle.