Little community support and consensus on this would be cool...
Several times in recent history, I have put up LFMs with "Please Know Quest", in the LFM. It's not because I am being elitist or hate new people, it is because of limited time and/or to eliminate a lot of unnecessary chatter about the quest/raid prior to entry.
Inevitably, I have had 1 or 2 people who obviously don't know the quest and it ends up with squabbling, babysitting, ect...
Please, please, please: If you don't know a raid or quest where the person who put up the LFM requests you don't join if you don't know it, DON'T JOIN. There are plenty of VoD, HoX, Shrouds, ect, where you can learn it and time isn't really an issue. Joining a raid where everyone knows it and wants to get through it quickly and easily just irritates the group if you don't know it and it was stated in the LFM. It also makes the leader look bad.