There are lots of reasons why a person may have problems with spelling. Some may have a hard time seeing the computer screen and may not notice a misspelled word. Some people may not be as educated as others, but that certainly doesn't mean they are less intelligent. Still others may be very well educated but may suffer learning disabilities that make them appear ignorant. I would never jump on somebody based on their spelling abilities.
Some people suck at spelling. Others suck at math, computer technology, chemistry or physics. Unfortunately, for the poor spellers, their flaws are more obvious when posting on a public message board. I would hate to see their input disappear because they are afraid to offend people with their spelling problems. I hope we can all remember that none of us are perfect and that all of us have important things to share here, regardless of how well we deliver our words.