Remember, kiddies: You do not take English classes in order to pass English classes. You take English classes in order to not make a fool of yourself when applying for a job.[1] If you get in the habit of at least *trying* to use decent grammar, spelling, punctuation, etc., when posting online, you will probably get an employer to make it past your cover letter without falling out of his or her chair laughing. Few people (unless they're looking for a proofreader, I suppose) expect absolute perfection, but the more errors your make per page, the more likely it is someone will take this as indicative of a generally sloppy and careless approach to tasks in general.

[1]Furthermore, people you meet on online dating sites will be a lot more responsive to your posts if you don't present yourself as an illiterate moron.