This complaint mainly stems from people who debate about the metagame of Yu-Gi-Oh! Of course, I'm sure this goes on in many other places; however, thus far this is the only place I have personally noticed it.
People who do not use proper grammar in their debate arguments absolutely drive me crazy. If they don't put the time into writing out their argument and presenting it nicely, why in the seven moons should I take the time to read it, understand it, and accept any points it might have?
My friend Swm from Pojo often engages in (one-sided) arguments with people over whether certain cards should be banned, reprinted, whatever. I hate that in most of the people fighting against him, their posts are filled to the brim with "lol," "epic fail," "pwned," and all these other idiotic internet terms and phrases. You DON'T write like that for your professor (and for those that do, I feel no sympathy for their ignorance and blatant refusal to learn English), so why would you write like that in a debate? At the same time, they expect us to believe that they have valid points and they are attempting to persuade us to believe their point of view, when half the time I'm focused on how terrible their writing is.
There's a place for "lol" and such...on MSN Messenger and similar programs, texting with your friends on the phone where it's more efficient to write like that (sometimes), maybe even in small notes students pass to each other in class. Heck, I would accept it in a literature of prose in which the characters' dialogue is "leet speak." But, in a legitimate person-to-person debate that should logically be filled with intelligent remarks? I don't think so.
From now on, I refuse to accept any arguments from people who cannot take the one to three or four seconds it takes to write out something in a proper manner. It really isn't that difficult. I'll never understand the reasoning behind this lazy writing. It is pretty sad.
Subject: ShadowBlade's Life Observations - 8/22/2009 - "no u noob lol" 
Sat Aug 22, 2009 3:44 am
