I understand that some people simply can't spell or don't have great grammar. And hey I don't claim to be perfect in that regard either, in fact a word smith could no doubt go through the grammar, punctuation and sentence structure of this very post of mine with a red pen and find many mistakes.
It is a car discussion forum, I don't expect it to be a spelling or grammar test. I realise that some people aren't great at spelling or still don't really know where commas should go or basic paragraph structure.
However what pees me off is when people are just plain lazy. By typing up a thread in text talk rather than plain English, it says to me that person is too lazy to make an effort, yet expects us (the reader) to make the effort to read through and interpret their mess. Often they are asking us a question, yet they can't make an effort to type that question up in a easily readable format. I just skip past those threads because if they can't be bothered typing in plain English, I can't be bothered trying to read their SMS type message.
Text talk belongs on phones. This is a forum, not a SMS. As an author of a message who is text savvy, it's probably a lot easier/quicker to type a thread in text talk. However as a reader, it's a lot more work processing a text message. For starters there is no universal text abbreviations. So often you have to first determine what the abbreviation is.
Second, we've probably all seen the tests which proves our brains only really process the first and last letters of a word, hence I (and I am sure most people) can read & process a paragraph of properly written English in the same time it takes to read a couple of lines of text talk.
Third - grammar. As said, I'm not talking about perfect sentence structure or correctly placing every comma or full stop. I just need some sort of punctuation in order to understand what the person is trying to say. Ok, I can get by without commas, but I cannot hope to understand a 10 line sentence with no full stops and/or capital letters...
I just think a bit of effort from the author of a thread shows respect to the readers. It's not that difficult.