Sometimes I switch on the subs to have a laugh. I've seen Ed Miliband written as Ed Miller band and Madagascar as Mad gas cars.
There's nowt wrong with using the odd American word, my computer is set to US English so it autocorrects to that language. People should sort out their own grammar/punctuation/spelling/spoken language before going on at others. In my opinion, written language mistakes are worse than the aforementioned words being used too much.
I'd say my spelling is pretty good, I make the odd cockup but that's only when I'm using my Ipad or phone, both of which have inferior keypads and I don't particularly like using them. What I do know is that none of my recent posts are as badly written as your initial post in this thread.
We are actually both singing from the same hymn sheet as we both appreciate good spelling, punctuation and grammar and the correct usage of language. I think that using "so" and "like" more times than necessary is not ideal but they act as filler for spoken conversation, hence why we don't use them in written posts. However, it's harder to justify spelling and grammatical mistakes like the incorrect usage of commas and there/they're/their.
(I should add that the evolution of language doesn't really bother me. Scholars in Roman times were complaining about some Latin words being spelled incorrectly by people so it's nothing new)