I don't worry too much about it unless is so terrible of grammar I cannot understand any of it. But if someone uses their for there or stupid little errors like that I really don't care I do that all the time by accident...now if I was writing a college paper or something that was going to be published I'd probably go back and fix all the little errors I've made...but just don't see the point for a non-formal public internet forum so long as I didn't type something totally unreadable. Also though I assume especially on this site a lot of times people posting are going through a lot and so their focus might not be so much on proper grammar...they are just going to want to let it out and find some support not have someone nit-picking at their grammar.