I agree that typo's and grammatical errors make for a very unprofessional look on websites and in emails.
I almost didn’t put my 2 cents worth in this post just in case I made an error.
If I’m posting something that is important like a website or a press release, I like to have someone else read through it first because it’s amazing how your mind tells your eye what it’s seeing. I used the word “lastest” instead of “latest” on one of my post and didn’t catch it.
I think we've all had those moments when we wanted to say, "Oops, can we have a do over?"