I don't really mind if people have trouble spelling, or use poor punctuation and grammar, as long as they're doing their best to deliver their message as clearly as they are capable of. On the other hand, if they are clearly being lazy, I don't see any point in forcing myself to translate their words into English. There is a difference between being unable to spell and not bothering to ensure that words such as 'the' are not spelled as 'teh'. There's a difference between using poor grammar and using abbreviations and acronyms which make the (many) readers have to stop and translate because the (single) writer was too lazy to type the whole thing.
As someone else said, if they put no effort into making their question readable, I see no reason to put effort into answering their question, or even reading it. Communication comes down to courtesy. If you want to be taken seriously, take the time and effort to do your best to be courteous to your audience. You don't need to go overboard or be perfect, but put in an appropriate amount of effort.
Have you noticed that answers tend to be typed more nicely than questions? It's interesting, isn't it? The type of person who is courteous and helpful enough to answer a question is likely to be the type of person who cares about others. If I see that someone has taken the time to make their question as clear and readable as possible, I see that they have respect for others and I feel inclined to help them.
I'd like to think that the use of proper English is usually done out of courtesy and a desire for efficiency. I think that's more often the case than trying to look better than others.
FFS, AYFIWCTPSGAD.