@Phantom Rider  
There’s enough sibling in Equestria that look nothing alike, and several cases of ponies who bear a striking resemblance to each other but aren’t related at all. Family resemblance is not a real thing in Magic Pony Land.

The question is, what happens when they notice how much alike they look, investigate some, and finally realize they’re actually long-lost siblings? And what will they tell the kids?

@OneOverTwo  
True. But anything can be made possible by diverging from canon in a way that enables it, so it’s probably best to stick close to canon for the purposes of this discussion.

@Scrounge  
This is, of course, just examples of when it wouldn’t work in universes that start off close to the canon one, yes?

@Soarinjack  
Yeah, that’s not a good enough reason. A stupid ship is one where there’s a clear and specific reason why it’s just plain not going to work.
 
Shining Armor and Chrysalis, for example, would be a stupid ship, because after what she’s done to him and his loved ones, he would probably want to see her imprisoned for the rest of her life, or possibly even executed. Likewise, Applejack or any member of her family being willingly involved with Flim or Flam seems highly unlikely. (Blackmailed into it, on the other hand, I’d buy. Those two seem like they’d stoop to anything.)
 
For a non-enemies example, Twinkie. It just seems to me like there’s only so intimate they could get before the odd-couple thing stops being fun and they start driving each other crazy.

@Scrounge  
Ofcourse it is. That would actually make a nice backstory/story. Finding out it just doesn’t work between two ponies. I fall in the camp of not seeing it as huge deal, if the personalities fits, but for others it’s a serious obstacle to a ship. Either viewpoint is completely legit.
 
I was more talking about people opposing certain ships, on the only ground they’ve never met in the show. Not as a personal preference (ie. “I don’t ship this”), but on a principal level (“this is a stupid ship”).

@PonyPon  
That’s both good and kinda bad, the latter because it also applies to ships that appeals to me and I want them to work but there’s that problem. Sunlight/Sunsetsparkle in particular is one I know is basically impossible but they’d be so compatible if only they didn’t live on opposite sides of the mirror.

@Scrounge  
I think it is.

@Soarinjack  
I’m hesitant to ship anyone whose lifestyle is heavily dependent on flight with an earthbound lover (Scootadash may or may not be an exception depending on my mood at a given moment). I’m just unsure about ships where one partner spends too much time where the other can’t follow.
 
So is “they’d be apart too much” valid?

@Background Pony #7669  
Pretty much this.
 
I mean, “they’ve never met” only works if you assume these ponies never, ever venture outside the town they were born in/live in when we first meet them.
 
Will the Wonderbolts never perform in Appleloosa? Or a town nearby, and Braeburn never bothers to go? Braeburn will never travel to Canterlot? etc..
 
There’s plenty of ways to bring to ponies together, without contradicting canon.
 
Don’t ship this, the only ship I have with Spitifre is Soarfire. Braeburn? Nothing.

No Braeburn, you’re not straight! Just confused.

@gittonsxv  
That it’s the same but with a city girl?

I’ve never understood the “they’ve never met” thing.  
I mean, if that makes developing a relationship impossible, does that imply that all of you with significant others were born face-to-face? Because otherwise you’ve “never met” until some point in your life.

They have never met. Have vastly different careers. Differing personalities.
 

@Ridley Wolf  
Lack of dudes leads to people to use more creative(?) pairings for straight or gay (especially gay) pairings?

@Ridley Wolf  
well soarin x bae has a city boy meets cow boy gay love thing going on but this?  
i do not even know what to say about this.

I have the exact same issue with this ship that I have with Soarin x Braeburn.
 
One lives in the pony version of the Wild West, the other lives in a cloud city that is probably at least a hundred miles away.
 
Under what circumstances would these two even meet?
 
Please don’t take the above comments as an insult towards your OTP.  
I’m just curious as to why people would pair these two.