Perhaps it’s a side effect of reading so voraciously when I was a child, but I’ve never had major issues with grammar. Although my grammar isn’t perfect (no one’s is, really), grammar comes pretty naturally to me. I’ve never had to study it to inherently understanding parallel structure or compound sentences or what have you. I don’t strive for perfect grammar, but I do strive for excellent grammar.
As a child, I would embarrass my parents by correcting adults’ grammar (because it was something my parents corrected in my brother and me, I didn’t yet understand at 4 years old that it was rude to correct adults when they used bad grammar). I’ve since grown out of that habit, but I still get a little nails-on-the-chalkboard feeling when people use incorrect grammar in the written word. For your grammatical delight (or perhaps you’re trying to learn English grammar?), I’ve found a gorgeous little infographic over at bitrebels.com about the most annoying writing mistakes (and yes, it does have an unnecessary hyphen in “most-annoying,” but we’ll let that pass for now…).
One mistake that this infographic didn’t include was when people end a sentence with “John and I” instead of “John and me, or they say “Jane gave it to John and I” when it should be “John and me.” Egads! And for me, one mistake I personally am frequently making is spelling the word “happened” wrong — I never can remember whether it has one “n” or two. Thank goodness for spell check! Which mistakes really make you want to whip out that red pen? Which mistakes do you have to keep catching yourself on?