I have no problem with people who have difficulties spelling but try to get it right, by using friends/dictionaries etc. I do have problems with people who [whether with problems such as dyslexia or not] just can't be arsed, because it's basically them saying that they prefer to be ignorant. I don't understand why these days ignorance is seen as something to be proud of.
And I do say this as someone with several family members and friends with dyslexia, all of whom try very hard, especially when it matters. They use dyslexia as an explanation for if they accidentally get it wrong, not an excuse for not bothering at all. I mean, I have horrific depth perception and pretty bad hand-eye co-ordination and was thus rubbish at every sport we ever played in school [I was so bad at tennis the games mistress broke out special balls which didn't bounce as high; they'd never needed to use them before] but it didn't mean I just gave up. I put in all the effort I could.
Personally I know I have always been lucky with spelling, but when I write I often try to stretch myself with words, and if I'm not 100% sure I know how to spell something, then I look it up. The whole reason that standardised spelling and punctuation was introduced was to improve communication between people, so they could spend less time on trying to decipher what the other person was saying and more time on understanding it and formulating a response.
And it does differ depending on what you want to get across. On places like this, if you want to just chat, and you're not bothered if some people can't quite understand then, then fine, be a bit lazy [I know my writing definitely changes depending on where it's being put - I often write stream-of-consciousness on forums, which I definitely wouldn't for work or for prose in fiction] but if you want to make a serious point in a discussion and have it considered, it is to your own advantage to make sure it's presented in a standardised manner.