One thing yet another episode shows is that the one thing Rainbow Dash is not is cool. Nobody is who is obsessing over it. It's a classical issue where one tries to compensate for an inner shortcoming with outside things that are not her. (Apparently I saw where this episode was heading.) When she manages to resolve that, she'll be cool. (I see this stuff all the time.)
And hey, her fear of failure is well-known and again shown clearly in this very episode. That might go away if she focused less on apprearance and style. ... Maybe her admiration of the Wonderbolts, who are stunt flyers after all, contributes to that focus on style.
When she does know what's important and acts on it, she's mature. But she's still not cool then, but actually more like Pinkie Pie. The two generally have a lot in common.
Like the last episode, this is yet another full reset of (at least assumed) character development.
Funny, when I see her so often associated in fan art with US patriotism and seen in collages with the US flag, I can't help but think of how the two have something in common, which is a lack of humility.
The enjoyable part was in episode performance, the hilarious absurdity of her imitating the other mane 6 ponies.
P.S.: Weird that they always have a filled trashcan ready at the runway, isn't it? And I'm also wondering why they started calling her "Rainbow Crash" and not "Rainbow Trash". She did specifically choose the trashcan for herself, so that's pretty fitting, haha.
P.P.S.: LOL, I wrote this minutes before Pinkie brought this one up. I guess that makes this a pinkie scriptum. ^^
P.P.P.S: I think Pinkie didn't actually want cotton candy. She just suddenly thought how funny it would be if the stand flowed over with it and then tried how far she can push the guy. xD