I’m fine with newbies when they’re in normal instances. Some people prefer questing all the way to the level cap, which isn’t a bad thing. You’re new to the dungeon? Use your map and ask questions if you don’t understand a mob pack or boss strategy. Communicate with your group. For the most part the newbies I meet are open to learning how things work, and some are even nervous about their performance. I’m a regular poster in the Newbie forum and it’s satisfying to help someone out.
It is a pretty theory that people should practice in normal dungeons and then go do heroic dungeons. However, it doesn't work in practice. I've tried getting people to crowd control in normals, and they complain it is too slow. They're not wrong, either. If it weren't for the aspect of trying to practice for heroics, there really wouldn't be much point in crowd controlling in most normals fights.
As a result, the only way to practice the new things you need for heroics--crowd control, damage reduction--is to actually run heroics. As such, I don't see a way for Icedragon to attain a mythical world where other random people he meets through the Dungeon Finder are going to know as much about Warcraft as he does. Everyone starts out not knowing, and then mostly learns from doing it rather than reading about it, and since they are all in one pool, they are just going to be a lot of groups that mix old hands with hopeful newbies. Personally, I kind of like that mix in general.
The closest thing to a good answer I can come up with is to drop the valor-point bonus for running daily random heroic dungeons. The valor point bonus was initially put in so that people will have a reason to run heroics after they outgear them. However, it's not needed any longer. Meanwhile, the heroic dungeons are clogged up with people who totally outgear them. If they dropped the valor-point bonus, then the only people in heroic dungeons would be people who have some heroic gear but are hoping for a little more. Groups would have a consistent gear level, and they'd also have a more consistent level of newbiness. The feel would be more like with levelling dungeons, where three out of the five have no idea and the other two are levelling alts and can contribute a lot of pointers.