The above photo is of an advert I saw tacked to a coffee house bulletin board in Chicago. Call me shallow, but that grammar mistake right there might deter me from calling a person to take care of my kids.
I don't know...maybe it's my English Major. Maybe it's my very grammatically correct parents. I knew how to avoid ending my sentence with a preposition at age six. My dad taught me a word a day when I was little. Erudite was the first of those. I learned that one around the age of seven or eight and used it regularly. Being called "precocious" when I was twelve, to me, was the ultimate compliment.
In fact, the photo below, quite nicely captures how I feel about grammar.