I hate it when that happens. I hate it when I join up with a group and someone says something like "hay gusy, my 60 friend will take us thru." I quit the group right about that point. I do love playing this game-- I like the strategy of different classes, and I like using the abilities the classes have at different levels to take on dungeons as a team. That's exactly why I hate being run through a dungeon with someone higher than me.
At least a few of you probably think I'm crazy by this point. "It's so much easier for finishing quests," I hear you saying. "Why would you refuse help?" That's exactly why-- because it's easier. I like the challenge of playing the game without help. Even wiping until my gear goes red is much more exciting to me than sitting around and watching a higher level character play for me. Yes, even Uldaman and even Gnomer. Are those places annoying after five failed runs? Yes. But even then, I'd rather go with a good yet low group than tag along with a 60.
Flame away if you want. Laugh at me for making things harder for myself if you must. But don't be surprised when, on my lowbie alt, I politely refuse your offer to powerlevel. I pay for this game to discover things for myself, not to watch someone else play.