I would say you can only truly say you can determine the quality of a work based on its grammatical correctness
There is no true way to objectively assess a written work. As a human being, you will be biased in some way shape or form. There is no escaping this fact. Therefore, there is no way you could look at something with complete objectivity. Language evolves just like culture. I suppose you could base your assessment on the current acceptable standards, but why would you? AgOoDwRiTeRmAyCoNfOrMtOwHaTiSwIdElYaCcEpTeDaScOrReCtBuTaGrEaTwRiTeRkNoWsThAtThErEaReNoRuLe StHaTcAnNotBeBrOkEnUnDeRtHeRiGhTcIrCuMsTaNcEs
In my opinion it is the message that is more important than the medium, but then again, the sentence above made me want to gouge my own eyes out, so I'm probably just full of crap.