In continuing with my observations made here, I wonder if the following way of preventing someone from spamming a commenting system really helps:
____________ Spam protection: Sum of II plus III plus IV ?
If I really want to spam this site, I can write a simple routine to scrape the string matching 'Sum of ___ ?' and then feed that into Google like this:
Google search: II plus III plus IV
And there you go! You are spammed!