How important is (good) grammar?

Sure, I understand that a bank needs perfect grammar or any financial services, law firm, etc, but what's your view on content that I am spinning that is legible but not exactly "perfect".

I guess my point is this: I live in Hong Kong and I am ranking local sites. English is widely spoken but understandably written English here can be slightly-off - so - would Google be more forgiving do you think for NON-US TLD's?