It depends on whether the poster uses the same "style" of writing each time. Repeated or constant errors do lead me to conclude that a person might be very young, handicapped, ESL, or just uneducated. If you want to call that "judging," then yes, I do judge them based on their posts and I choose whether or not to read their posts accordingly. An occasional mistake (or misteak, lol) doesn't ping my radar, but someone who uses "excess" instead of "access" multiple times in one post...I just assume they don't know any better or they don't care.
Elsewhere on the web, there's a frequent poster who capitalizes every word in every sentence.
It's Like This You See And They Never Use Punctation Grammar Or Spell Check.
They may very well have something important to say, but they have gone out of their way to write in a manner that is difficult to read. I figure it's my loss, so I just skip over his/her posts now and don't even bother reading them at all.