I would like to make a few additional observations since this thread has outlasted the original posting.
I personally do not mind being corrected if I have made a mistake. To take offense would mean not learning something new. Further, when I do offer a correction it is done in good faith and is not a gotcha.
For those who do bristle when this happens then you have the option of not posting to a public forum.
With all the information available on the web it is relatively easy to check what you wish to post.
APUG would be very dull if everyone always stayed on topic.
I have been told (on other forums) that I shouldn't correct other peoples spelling or grammar (I know it can be a bit annoying) but the usual reason given is "they might not have English as their first language".
I have a few friends for whom English is their second language and in a couple of cases, their third and they have all stated that they want to be corrected so they can learn the correct use of the language rather than carry on repeating their mistakes.
Like Gerald, I don't correct people for the joy of proving myself superior, I do it so they know the right way the next time. If some people take it the wrong way (which they invariably will) then I will have to live with that.
Oddly enough, and still off-topic, I used to make a bit of spare change when I was a freshman in 1976, editing papers for Seniors. (well, the Canadian equivalents) The ironic part is, most of them were on scholarships, and I was a dyslexic musician who had taken 6 1/2 years to complete high school.