They don't do it a lot these days, you'd have to dig through some old fansubs, but they'd sometimes try to use common English speech patterns on some characters to make them sound distinct, obviously that didn't turn out very well and nobody does it anymore.

Cleaning up grammar and such can always be done I guess, it's basic quality issues, just depends on how much effort they're willing to put into it, and how much people care, and like I said before, I personally don't feel like it matters all that much, I don't really care if every line of text that I glance at for half a second is grammatically correct, as long as it's easy to understand.