You're entitled to disagree. However, whether or not someone is speaking perfect English (bet you didn't know that it's capitalized!) is certainly not for you to determine.
I believe that hearing AND deaf are BOTH capable of adopting exceptional English and language skills. It's just a matter of obtaining and maintaining a proper education and the desire to speak/write properly. NO one is perfect, that's for sure, but I know some deaf folks whose English skills have surpassed those of "normal hearing folks."
As for the slang, people have a choice as to whether or not they want to use it. It just makes them LOOK unintelligent, even though that may not necessarily be the case. Over the 'net, it's just easier to shorten words and not worry about capitalization and grammar.
Keep in mind, though - most of the communications you have are more than likely over the Internet and through communicating via ASL. So, NO, of course you're not going to see "perfect" English. :roll: