Lets start off simply here. Rarity's element is the Element of Generosity, right? And Generosity can have it's ups and downs. A downside of this is proven in the limited knowledge that we know (As of the second of January, 2014) of the episode Rarity Takes Manehattan. It is proven in the episode's summary from AT&T U-verse:
"Rarity’s love for fashion takes her to Manehattan for Fashion Week, but her excitement is soon diminished by a fellow designer, who has decided to take advantage of her generous nature and pass off her design ideas as their own."
The words take advantage of her generous nature are the key words in the sentence. Generosity is an element of someponies that is very easily taken advantage of. If you're reading this after the airing date of Rarity Takes Manehattan, then you'll know what I mean. (Man I really want to see that episode!) I find, though, that although holders of the charm of Generosity are very gullible, especially when least needed to be, they can control it. And, well, Rarity, she will, I guess, find that small part of her that really IS gullible and let it take over. Now, these may sound like my predictions for the episode Rarity Takes Manehattan, but they're not. I'm trying to say something here. And I'll move onto my next point, to show you.
I read somewhere, or heard somewhere, that originally, Rarity's element was going to be the Element of Inspiration. I can't remember where I got that from, but I'm pretty sure I heard it on a you tube video. Now, when I heard this, I was like: "Whoa!" I was seriously shocked. I really thought that Rarity's element was really suiting to her, especially in the episode Suited For Success. The reason that I was shocked was because I, personally, thought that the Element of Generosity was the most suited, and that no other element that the writers could come up with would be any better. And then, this came. It actually WAS better, and a bit inspirational (Pun intended) . Then, later in the video, it said that the only reason why Rarity's element WASN'T the Element of Inspiration was that the writers thought that it would be hard for the aimed audience to understand. (They REALLY weren't expecting us, were they!?) And I lol at this. Seriously, I lol. Literally. I'm not kidding. I really laughed when I found out why her element wasn't the Element of Inspiration.
This looks like it's going nowhere, doesn't it? Well, I have some more. They probably weren't planning this episode that early on, but if this was a Season 1 episode, it'd probably be in planning by then. And if it was, well that'd certainly be interesting if they did end up choosing the Element of Inspiration. 'Cause they might not have thought it out well enough, and then they'd have to erase all episodes before it, so they could change her Element from Inspiration to Generosity. So, basically, what I'm saying here is that the Element of Generosity was kinda CREATED for this episode.
Ps: If you're a youtuber and you do headcannons, pls do this one on your channel. Especially if you're Ink Rose or Brony Curious.