I'm delighted to see this blog from marketing genius Seth Godin having just had a similar discussion with a colleague following my rant about Dunelm Mill and their inability to spell "drawers" - of which they sell quite a few.
"As long as you know what the person is trying to say, what difference does it make?" she said.
My argument was that if it doesn't matter, then why not get it right? Because IT DOES matter. I say this because I frequently choose the supplier that knows the difference between "you're" and "your" or "it's" and "its". My thinking is that if they can't get that right, then can they be trusted with the other simple stuff?
And sometimes, the smallest change can alter the meaning of what you're trying to say. We once stopped at a restaurant en route to a party because when we asked the host if there was dinner, said: "No food served." He actually meant "No. Food served". The complete opposite.
Having been on the end of thousands of press releases, if there is a mistake in the first paragraph, I won't read on. There just isn't time to correct people's spelling when you're on deadline in a busy newsroom.
Apparently, 99% of press releases get binned. So one of the simplest things you can do to avoid being binned is to check your grammar and spelling. Always, always ask someone to check it over before you hit send.
Remember: "an apostrophe is the difference between a company that knows its sh*t and a company that knows it's sh*t."
*edited as I'd originally spelt "Dunelm" incorrectly! Oh the shame!