I've grown used to it online. I'm sure I've even contributed to it online. We put up with much more than we used to. The internet has lowered our threshold for correct English.
I do my best to be grammatically correct. I try to go beyond simple spellchecking. I try to give some polish to my posts. However I realize that I'm not a great self-editor. I glance over my words and tend to miss obvious errors because I know what's supposed to be there.
I've never had my writing picked apart and corrected by a talented copy editor. I'm not sure I want to go through the experience as it would most likely convince me I don't know how to use English at all.
Copy editing is a particular skill. One I haven't mastered and one I don't think I have the knack for. It must take a certain mindset and a certain set of skills that I don't have. So reading about Copy Editing at The New Yorker with Mary Norris gave me new insight into how much writing can be improved by a good editor. I have to stick with self-editing for now but I'll try to do a better job of it.