Intentional shorthand and text-type for the sake of brevity in comments is one thing. Pushing words out of your crowded head in the form of a scribbled first draft, before the fleeting thought passes and is lost forever, is one thing; but if you own the thread, and you've posted some God-awful text to be damned, fix it. For the sake of goodness, for the love of Pete, delete it, and start over. Anybody who's interested in what you have to say will wait.
Just so you know, that whole, "It's only Facebook," thing only works for folks who are being lazy on purpose. Writers rarely have the luxury of being lazy on purpose. Find your pride and fix that shit. Respect the craft.