I have noticed a consistent lack of spelling and grammar skills among the creationist set. Maybe their distaste at learning science extends to a general distaste of learning.
Get it from the same teacher who teachs englush and speling who teeches evolution.
From my experience, that does seem to be the case. And also explains their position, because I've found that people who *do* sit down and learn the material don't *stay* anti-evolution creationists for long. It's only by maintaining a strict self-imposed ignorance (via "Morton's Demon") that they're able to cling to beliefs like "there's no evidence for evolution" and "evolution is just a crumbling atheistic conspiracy", etc.
It's similar to (and in some ways, a direct overlap with) the results of the study which found that people who were incompetent at certain tasks were *also* incompetent at recognizing how poorly they were doing at it (they thought they were performing *really* well...) It turns out to be a vicious cycle -- if you believe that you don't have any need to improve, then you don't take any steps *to* improve. Cluelessness breeds continued cluelessness. And on the flip side of the feedback loop, lack of knowledge facilitates continued incapacity to recognize how much better you *could* be doing, which reinforces the overconfidence in one's performance.
Don't want to step over the line into ad-hominism, but have you ever noticed how creationists very often confuse singular & plural? As in, "all those scientist are liars..."?
I know there's some cognitive problem where the sufferer has problems forming plurals of words, or has problems using plurals in their proper place & context, but I forget what it's called. (Maybe if I call up that museum, you know, "smith" something, and ask someone. But I digress...)
I worked with a software guy once who had this problem. He did have a strange sense of what constituted good code, but he wasn't necessarily a bad coder. And he wasn't irrational or creationist in general. Yet creationists seem to make this mistake much more often than mere chance. It's weird.