Rule 7 doesn't really fit for me. The usage to which you object is so pervasive that I think protesting it is literally pissing in the wind (I love using it like that, you'd rob me of that?).
Also, since you're citing the 'long' history (1778) of "ain't" as validation, 'literally' as an intensifier has been in recorded use since the 1680s, and used by some pretty notable writers.
Aside from the ones which are simply bad grammar, this always comes down to a battle between prescription and usage. And we each seem to draw the line in different places, what induces the red mist in one person seems a cute little quirk to the next. For me, seeing 'cliché' used as an adjective (rather than 'clichéd') flips me out.