At these parties, what Applejack hated most was the lying. 

"Charmed, ah'm sure." 

It was more than just pleasantries, those bits of social shorthand that, under inspection, become nonsense. 'I'm fine' or 'have a good day' are mostly reflexive anyways, barely meant.

"Been well myself. And y'all?"

It wasn't even particularly egregious or offensive. On the whole it was mild. But it was so [i]pervasive.[/i]

"You don't say?" 

It was petty self-aggrandizement or rumor-mongering,   boasting, character assassination with subtle jokes - and delivered oh so carefully. That was the worst part, really; how she had to actually pay attention. If she allowed her eyes to glaze over and simply nodded along, who knew what she might agree with? 

"Ah'll be certain to ask her about that." 

It wasn't random, after all, nor was it mindless. Each half-truth, white lie, fib, came from ponies who were stirring the pot, working the crowd, trying to ooze their way up the social ladder. Usually by stepping on anypony 'beneath them'.

"'Scuse me, I think Ah see my friend…" 

So she would smile and nod and eat the snacks that were almost - but not quite - tiny enough she could ignore that they were over-salted and under-crafted, and excuse herself at the first possible moment to enjoy what she loved most about these parties:

Rarity's smile. 

"Oh [i]there[/i] you are darling, I was looking all over for you!" 

Her friend took to each crowded ballroom or shaded lawn or gently swaying airship like, (as much as she would hate the expression,) a pig to mud. She was completely in her element, wallowing in pleasantry and polite fiction, scoffing at rumors or cutting through boasts with a keen wit. And somehow, despite fitting in perfectly, she was beautiful without being stained. 

It was probably that smile.

"You simply [i]must[/i] meet him, Applejack, he writes the most hilarious articles—" 

It appeared at each greeting or parting, brilliant and ephemeral as a shooting star. Rarity smiled at everypony, regardless of station, or costume, or even how pleasant their company was; a brief glimpse of pure happiness, shining through the ritual and pomp, an irrepressible truth. 

"Oh, there's Fleur! Come along, we'll say hi!" 

It was almost reason enough to come to these parties, seeing that flickering smile illuminate her friend from the tilt of her ears to the tap of her hooves. 

"Oh dear, it [i]is[/i] getting late!" 

Almost. And sometimes, after the small talk wound down, the buffet was cleared, the guests were trickling out, and the two of them were yawning their way back to a homebound train over the cobblestones and under the gaslamps, Rarity would say

"What a lovely evening. Did you have fun?" 

[i]No.[/i] 

Applejack's feet would be hurting from fancy shoes on marble, her stomach protesting overly rich food, her memory relentlessly replaying some stupid thing she said, and home and bed looming large in her mind... 

But she would bite down her retort. And instead of letting the evening die, she would say

"Ah had a wonderful time." 

Then there would be one last smile, just for her, to carry home in her heart. 

And she would think that, maybe, a few small lies now and then were tolerable.