WITH LOTS OF SHOUTING, NAME CALLING AND FINGER POINTING!
POOOOOOOOOIIIIIIIIIINNNNNNNNNTTT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
No but seriously I'm like you OP, I come across with knowledge of what I'm arguing for and against. Open to the other person's side of the argument in case there is a fact that I was either unaware of or in case I'm actually just flat out wrong!
The most annoying thing that people do when they argue is completely ignore the other side. I find that very very frustrating as many times I know for 100% fact that what they are trying to argue against me with is wrong.
Also one of the annoying things other people do when arguing is when I've been having a discussion (not even necessarily an argument) for a few minutes listening to the other person's point of view while putting mine across, then eventually coming round to realising that I was in fact wrong about some aspects of my argument or even my whole side of the argument. And then when I realise I am wrong, and more than anything else I'm interested in the actual answer to the discussion not whether I "win" or "lose", the other person then feels the need to rub it in my face that I was wrong and they were right. Rather than realising that I was open to their side of the argument and saw the error in my ways and in many cases even apologise for taking any other side than theirs.
People I know seem to lack the ability to have a civilised discussion, unable to come to some sort of mutual agreement or any sort of good sportsmanship. And it usually does resort to them name calling, shouting and finger pointing towards me while I sit there and lose more and more faith in humanity and slowly make me dislike them that tiny little bit.
So basically the worst thing other people do is to have no manners during a discussion.