I hate 2 types of responses that make up a good deal of the traffic on the forums.
1. I hate people that come onto a thread and make broad, generalist statements about the reality of the game as if they have God speaking in their ear:
"*Every* melee DPS *has* to have 18 strength and *has* to have power attack".
This simply isn't true, there are advantages and disadvantages to every choice in a build and some choices will have a greater cost than others. I would suggest that people learn to make suggestions, or observations. Nobody likes being told they are "wrong" and usually they aren't. Personally when I make a post I'm not looking to be told whether I'm right or wrong, I'm asking for some perspective on the benefits and costs of the choices I've made in a build. It is much better to help, suggest or advise rather than generalise or command.
2. I hate people that come onto a thread and say something like:
"Dude, this is a game, we all just want to get along and have fun! I'd say if you want to build your wizard/sorcerer multiclass then you should go right ahead and do whatever makes you happy man! Peace out!"
While the above is true it really isn't constructive, it doesn't increase anyones knowledge of the game, it just becomes a post that everyone skims over in search of something worthwhile to read. I will note however, that sometimes it can be good to combine a little bit of this with some solid advice as a gentle reminder to perhaps reassess their priorities.