I notice grammar mistakes everywhere, written and spoken, scripted TV and reality TV, social media and in social situations. It's not just all the sentences that end in prepositions, because that's not a "hard rule", or the use of adjectives where an adverb belongs, what gets to me most is the constant improper use of "me" and "I". Sentences don't start with "me", but yet I hear "Me and so and so..." All the time! When a sentence includes multiple people it seems no one knows what to do!! You know it's really bad when, on a scripted TV show, where a professional writer wrote the line and an actor who is portraying a character with a degree in English ...Is making simple to avoid grammatical mistakes! (Saying "I" when the correct word was "me") I have observed this downward trend with grammar, it really became worse around the time reality TV blew up, but it was bad before!! I believe if you want to make a good impression, you should attempt to speak well! I feel like people know good grammar when they hear it, but don't know how to implement it.
I realize that the post was written this way to be ironic, but it is a very good example. I think that as we get used to using computers and texting on phones, spelling and grammar is falling to the wayside. My grammar isn't what it used to be anymore either. It may be an unfortunate side effect of living in an age of spell check.
In general the American grammar and spelling is usually fine. Sure, not everyone knows where to put a comma, or what a semi-colon is used for, but as long as we understand them and they are able to read and write to an extent I do not see it as a problem.