The beauty of Rainbow Dash is that she’s shippable with anybody. Some characters are just ship-friendly.

@BG pony
 
You know I’ve gone into this time and time again…Raridash REALLY isn’t that much of a stretch when you think about it at all.
 
They never really hated each other. In fact, judging from “Sonic Rainboom” Rarity understands Dash better than most would think, given they both know what it’s like to have big goals in life and not always feel good enough to achieve them.
 
Dash saved her life twice, and was actually the first to apologize to Rarity in “Dressed for Success”. In fact a lot of the scenes people point out in which Dash isn’t to happy in her company can be explained by Dash, just not being into the same thing, nor having much patience. That doesn’t mean they can’t have a deep friendship. She has that same issue with her other friends.
 
You could also say they have similar character flaws. They can both be vain, but are good at heart and make the right choices in the end for the most part. Plus between AJ and Dash, I imagine Dash to secretly care more about how she looks and enjoy some pampering, striking some cute common ground between her and Rare.
 
I don’t find it too absurd, either, that Rarity would have at least a little crush on her savior, nor do I think Dash would find Rarity unattractive.
 
I think a mature, assertive Mare, like Rarity (Or Applejack) would be good for Rainbow dash, given she can keep her ego in check, without being hurtful, but also encourage her to do better. To bring some direction into her life, and better her as a person.
 
Secondly, Rarity’s trade involves complimenting the pony form and anatomy. Rainbow Dash, being an athlete, exemplifies physical perfection. I could see her being at least mildly intrigued. Wouldn’t be too difficult for a lovely mare like Rarity to get Dash’s attention either if she made a move.
 
Raridash also just has a lot of the same “opposites attract” charm as Rarijack, but with a touch of the “classy vs. electric” charm of the Octavia/Scratch ship, making it extra appealing, IMO.
 
There are several instances that a friend of mine, called freezingshock brought up. To quote…”In Dragon Quest they were just hanging out and were apparently planning to have dinner together. In Sweet and Elite, there is this little scene in which Rarity hides behind Rainbow for protection and later she uses things she learned by conversing with Rainbow to impress the Canterlot elite, showing us that they do converse and that Rarity finds their conversations interesting enough to pay attention and remember. And in Sonic Rainboom (again), Rarity was the one who insisted they had to go to Cloudsdale to be there for Rainbow, and she even volunteered to be the test subject for Twilight’s flight spell. In Read It and Weep, Rarity was there along with Pinkie to watch Rainbow fly, and she was clearly having a good time. In Ponyville Confidential, Rarity is very into the idea of having Rainbow join them in the spa. And there’s probably quite a few other moments I forgot about. They’re definitely friends, no doubt about it.”
 
So the connection is there, and there’s a lot of deep empathy, and parallels between these two that totally validates this ship.
 
Certainly better than any argument I’ve ever heard heard AGAINST this ship
 
Furthermore…Even some of the most unromantic people have their moments…by your logic, Rainbow dash will never have one like this. Dash softening up here and there is kinda the charm to shipping her with a more feminine person

Oh come on, even shipping these two casually demands some serious stretch of the imagination, but to think of Dash proposing to anyone is beyond OOC for her… she has the romantic and emotional depth of a cinder block. That marriage would be annulled in five seconds flat, forget ten.

Proposals always bring out the sap in me.

@Blackbewhite2k7
 
I wouldn’t say canterlot for rainbow dash, the wonderbolts live in cloudsdale I think.
 
But yeah, I can see what you’re getting at I suppose.

@sixtyfour215
 
Busy people can be in relationships, too. I’d say the fact that these two are so goal motivated adds to the empathy and connection between them.
 
Both of their dreams will ultimately take them to Canterlot.

@Robomorons
 
So…Rainbow is the new spike then? And Spike is the new Dash? Either way…Raridash. So, yay.

Eh, I’d rather them be friend shipped together, rarity and dash are to busy to have a serious relationship with anyone.

Awwwwwww….Spike is proposing to Rarity.