My brother is VERY badly dyslexic. It is a fully recognised condition as you should all well know, and he struggled very badly at school due to this, and was bullied quite badly for being 'stupid'.
Dyslexia should not be confused with stupidity. Spelling mistakes are not just due to dyslexia, they are due to simple laziness and ineptitude.
I think posts like this show a simple ignorance to the plight of people who are less fortunate than you. You should consider yourself extremely lucky.
Spelling mistakes irritate me as well, people should be able to speak english I agree, but posts such as this one aren't really going to help...