The middle picture is the rape attempt from Seeing Red. Not exactly something you want to be thinking of everytime you look in the calendar.
"Let's see, dentist at the 11th, date with Eric on Thursday and oh, Buffy being raped."
I'm not sure if the person who picks the pictures for the calendar hates the Spike/Buffy relationship, is lazy and don't want to browse for pics or have a peculiar sense of what's appropriate, but I think it was a bad choice.
I don't have the calendar myself, but as far as I've heard, the rest of the months have good pics, so if you put a post it or something over the middle picture, I guess it's still worth buying.