I think that what he's saying is that if you add a " ` " (backtick) to your email's spam filter, it will catch additional spammers trying to get around your current email filters.
I added a new filter in communicator, in the subject line field contains I added a backtick, thats generally the first key above the tab button before the number 1, also the " catches a few more.
I know where the ` key is, but I still don't have a clue how adding that to something in your filter helps you. Are you saying to add just that as a separate entry, put it in front of some wild card, or what?