Thank you.

@Wilhelm II, Kaiser
 
Well, OK then…prepare for a bit of a long winded explanation though.
 
It’s actually not as implausible as some people make it out to be.
 
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.

I just vant to know how ze ship works.

No, I mean, explain how it vorks.  
I mean Dash hates fancy stuff.

…Some people enjoy Raridash? Not every Rarity shipping is going to be of AJ and spike? I don’t know what to tell you, man. If you don’t like it. There’s always filters.  
VVV

Points at the Raridash pic  
Zis fuckery, explain it.

@Wilhelm II, Kaiser
 
…Wut?

Loads a gun and points it at OP  
You vill explain zhis fuckery?