Few weeks ago I change theme from Blix to one that I've made my self. I've been using Blix since the start two years back.
The spam was really horrible but I thought that it came with the age of the blog. To my supprise the spam count dropped from around 1300 per day to around 50 per day the same day that I switched themes.
I cant really say for sure that it has to do something with the Blix theme, but for sure this is strange.