As a college professor, I do understand when my students make occasional errors in their papers. It's not a big deal. But when it becomes a pattern, it does take away from the elegance of the paper, even when it doesn't impede my understanding. I don't think I've read a really well argued paper that was riddled with grammatical errors. So while an error here or there isn't a problem, I think it pays off when people (at least my students) put care into their grammar.
But when I correct a point and they continue to make the mistake, that bothers me.
As for affect/effect... when you're considering the issue of cause and effect, effect is a noun and affect is a verb. For example: "Exercise has a positive effect on depression." vs "Exercise affects depression."
However, affect as a noun can also refer to "mood" or "emotion" as in "She has a very flat affect and I never know what she's feeling."





ARGH!
