To contribute to the discussion, if you're talking about some greenie that dropped and you say "u want it" then nobody is going to care. If you're going to try to convince someone of your scholarly opinion then "u agree" is probably not the best way to go at it.
I don't usually mind if people write their or there or they're. I'm not a native speaker myself, I can only do my best and try to remember when to use "fewer" and "less" again. No doubt I make plenty of mistakes, so it'd be hypocrite if I'd judge others. However, it just seems rude to me when someone opens a trade window to my mage and goes "wter plz". Would it hurt you to ask "could I please have some water". It's just, I dunno, language is more than just conveying a message, request or opinion. You can express so much with it and respect (and gratitude, in this case) is one of those things.