it's like when Saphire Shores told Rarity she's never heard of her.
the upper class of Equestria don't seem to know shit XD

Perhaps it is my natural paranoia, but my first thought as to why Fancypants was so accepting of Rarity and the other five was because he ACTUALLY KNEW who they really were, and just pretended to be clueless.

That is how he maintains his status -- he pays attention when everyone else doesn't, but pretends to be clueless thus making all of his "enlightened" opinions appear to be upper-crust instinct.