This particularly applies to non-native English speakers who find our complicated language hard enough and are less likely to pick up the gist of your message.
It's so easy to make a mistake. We all do it. But it's really hard to check your own work. You know what you intended to say and read the script as if that's exactly what you wrote. Another pair of eyes is needed to bring a fresh look to your work.
Many's the time when I've come across a website full of mistakes but when I try to contact the company it appears that they've stopped trading. Cause and effect?
A good example of a sentence meaning something completely different from that intended by the writer is the following - and it wouldn't have been picked up spellchecker.
From the BBC Sport website this morning:
"Murray
is pulling out some of his tricks now, fainting to go down the line, then
flicking crosscourt at the last minute."
Feinting was the word he needed.