I have Outlook 2003's junk mail filter set at the 'low' threshold - this catches a big chunk of my spam (I receive about 60-100 per day, 80-90% of them are caught by Outlook) and I have never had a false positive in the months I've been using it, so I no longer look in the junk mail folder, and instead I just empty it from time to time.

I recently received a spam that bypassed the filter, and I found the subject line amusing:

"Re: %RND_UC_CHAR[2-8], his head lightly"

Looks like the spammer's software to create the stupid-random-string-of-characters didn't work too well in this case; the MIME was also improperly formatted. It arrived in the middle of a bunch of spams that all had similar problems - perhaps the spammer was dogfooding an unreleased version.