On a forum such as this, grammar isn't important, what's important is that all can feel comfortable posting comments and trying to get their respective opinions across.
However, in business, the more adept you are with the written word, the more professional you will appear.
I've seen written quotations that make me wince (not just in window cleaning) grubby, hand written scrawls on a piece of paper, littered with spelling errors and appalling grammar.
Or flyers with grammar that looks so cack handed. This is where your command and understanding of English is important.
A well written flyer may well get you business, ditto a well presented and professional looking quotation.
But it is bad form, even in jest to criticize the writing skills of others on the forum.
Ian