I'm pretty tolerant when it comes to grammar or spelling, I guess that is because I don't care much about how I write myself. The only thing that annoys me is this 'leet-speak' with things like 'u r'. What's the point? In exchange for saving four letters you make the text unreadable. I agree with Nod. As long as it's not confusing it really doesn't matter.
PS I actually had no idea that it's important whether I use 'fewer' or 'less'. I would just use whatever sounds right