Hey, I agree with the meaning of blonde hair. :>
So, I'll share some of my effect theories.
"Knife" - I know everyone must think so, but Madotsuki started killing because she's got crazy with her freaked out life and it was an "alternative" she chose.
"Poop Hair" - probably girls that used to bully Mado throwed poop in her hair. (I always think so. ;A;)
"Cat" - when this effect is used, characters are attracted. It must mean that Mado got a cute appearance once to get attention.
"Witch" - I always associate this one to Halloween Day memories.
"Severed Head" - I associate Bird Girls to popular classmates that used to intimidate Mado. So, considering the effect is found on an area full of crazy Bird Girls, it must mean her classmates tried to decapitate Madotsuki once. >:
