Bear in mind that WoW has a variable learning curve based on familiarity with MMORPGs, time spent playing, coaches, and aptitude. There comes a time though, when folks should be pretty self-sufficient. The argument "I'm new" no longer holds water. For example, it goes without saying that hunters should always check their ammo supplies before going into instances and in general, clothies should let the tank pull.
Clearly by the time someone zones into a raid their rookie mistakes should be behind them. I've often heard level 40 as a cut off for newbiedom. Personally I expect someone to generally know the rules of the road by the time they're doing Outland instances, even Death Knights. Do you have a general rule for when you expect competence? In essence, when do you go from newbie to n00b?