Few things make a worse impression than poor spelling and grammar. The way I see it, if someone doesn't care how their writing looks, what other things don't they care about?
OMG! I think I might be in trouble! I can usually spell pretty good but my grammer sucks! I'm sorry, I tried in school, I really did, but I just couldn't get it. My strong point is numbers. If we could write letters in numeric code I'd be all set. LOL
But seriously, I have written a few emails that welcomed some new people to NB and got good responses. Commenting on something in their profile shows sincere interest and will usually get a positive response. At least that's what gets my attention.