Are you talking about ELEMENTARY mistkakes like misspellings? ("elimentry")
One thing I tell my customers when they give me copy to post on their site, RUN IT THROUGH A SPELL CHECKER! Then have 3 other people read it who have never seen it before. Ask for suggestions. It is amazing how your copy, which makes perfect sense to you and the rest of your buddies who you sit at the local bar with and share war stories about all the moron customers you have run into that day just before the bus crashes into the building next door and .......
You get the idea.
Make your site professional and it will help keep those customers you get from the search engines.