It took me a while but I finally found out how to use filters to block spam from my analytics.
I currently have the following filter pattern applied to 'campaign source'
I've just noticed a couple of new spam bots that have recently showed up under my Referrals section, but now it won't let me add any more to the filter pattern due to the character limit.
What is the best solution to get around it? Do I just have to set up an additional filter?