Atrociously bad grammar can certainly break you. In real life, people tend to form first impressions of strangers from the way they dress, talk, and behave. On the internet, you form first impressions from their writing ability.

The way I think is: If you can't be bothered to make your post easy to read by following some basic language conventions, you probably don't put that much thought and effort into what you're writing.

It also, to be frank, makes me think you're dumb. "If you're uneducated in language, you're probably uneducated overall." It's not a very fair assessment, but considering the importance of language as the primary medium by which to communicate thoughts, I think it's not that unreasonable. (Of course, I make exceptions for people who are clearly second-language speakers.)

But good grammar alone doesn't make you. It's not only important that you get most of your textbook grammar rules right; you also need to structure your post in a clear, logical manner. If your thoughts are scattered all over the place, and you jump from one point to another and back to the first, I'd think that you don't really know what you're trying to say.

Even in places where communication is abridged and real-time - basically, emulating speech more than writing - the basic rule of "make yourself comprehensible" still applies, although the textbook rules are more relaxed. I wouldn't, for example, expect someone to capitalise the first letter of every sentence and end with periods if they're IMing me. But I would expect their spelling to be good enough that I don't have to guess at what word they're typing, and if I'm holding a sustained conversation with them I'd expect their ideas to be coherent.

I don't think it can break you completely, but I find it hard to respect and listen to someone who can't manage to use the proper form of the word your. Like when someone says "your wrong"... as if to imply that I own a wrong. I understand that there are typos and grammatical errors but when they are compounded they reduce the legitimacy of one's argument.

ya it breaks you !!!when ,you use to be regular on social networking sites ,the chating language which people use is too short cut and it slowly slowly converts us also to change our talking language

Personally I look at someone shoes to get the first impression. Dirty or oil stained shoes can mean a hard worker. Fancy dress shoes usually means that they means business. But on here, I cannot see your shoes so I make up for it by your grammar.

In a chat window, like MSN or Steam for example, you can get away with it, mostly. But still not always, depending on how comprehensible your text is... Saying "thre u r i waited 4 ur msg omfg y u had 2 b afk atm wtf grrr y?" is probably gonna get you ignored (again). (to be honest... I don't know how these guys understand themselves...)

In forums or a website like this one that will probably get you bashed or flamed or made fun of, or simply ignored as well. It's often quite easy to perceive much of your personality just from the way you write and the way you organize your text, and even your age can be sometimes guessed.

I've been playing an online shooter for more than three years and during that time I could distinguish the eager ones, the frustrated ones, the nice ones, the fun ones, etc. I could even guess the age of many before they even told me. (It happened here too, in a debate about Sega vs Nintendo...)