Do I judge people by anything? Let's not pretend here, hell yes we all do. On the Internet you don't have much to go on but for what they write and how they do it, so it becomes essential for how you render your view on people.
What's worse, is that suddenly everyone's a dyslectic. We're not talking the normally estimated 5-10% of the world's population. Being a dyslectic means you have to try harder, and one can use a built in spell-checker (Hello Firefox Dictionaries) and other aids to make life easier, and I know many dyslectics do. The real ones, not just the lazy people that need an excuse for not trying harder.
To make a comparison, no one expects a blind person to amble around crashing into things without a helper dog/cane; while shouting "I'm blind leave me alone!". He's still blind, this is an explanation, not an excuse.
And you can't blame the media. "LOL IT IS THE INTERNETZ!" is not an argument. Sure, life on the Internet isn't a perpetual essay either. The whole idea is about putting forth your thoughts in a sensible, easy to understand way. Your output is judged by how much effort you put into it - and this includes your writing.
For me? There's grades in hell. If someone can't figure out the difference between then/than, they're/their/there or whatnot that's one thing, but when they think LOL replaces a period and Ur is a possessive pronoun or worse, when they think "LOL?" is a valid retort; then yes, you're losing points in my book. Points in how serious I take your thoughts.
I have a tendency to do horrible run-on sentences myself, but I do try. And I think in the end that's where you have to draw the line. Try, don't just throw around excuses and breeze by.