The genie driving Lickity-Split crazy when he won't grant her wish for a perfect day until she completely describes how a perfect day is supposed to be. Fed up, she wishes for ice cream, but then he wants her to completely describe that too.
From "The Glass Princess" comes this snarky line.
Megan: Sorry. Danny is feeling a little rambunctious today.
"The Magic Coins" has a surprising amount of snark, particularly from Spike.
Megan decides that singing a song would make them feel better as they trek through a desert. Upon its conclusion, she asks if it helped; Spike says it just made them more exhausted.
Then there's this.
Heart Throb: Spike, I think these hedge animals are alive!
Spike: Of course they're alive, Heart Throb. They're plants!
In "Crunch the Rockdog", Truly is about to be turned to stone by the titular villain. Wind Whistler (accused of lacking feelings by the other ponies due to her Spock-like personality) uses Reverse Psychology by pretending to be heartless to stop him and letting him do it. Especially funny is this line:
Wind Whistler: I'm perfectly serious! I've been surrounded by these romantic idiots for so long, it is refreshing to find one such as yourself.
More snark in "Flight to Cloud Castle", this time from Locket:
Heart Throb: (while being chased threatened by an undine and a salamander) We've got to stop them so that Garth can awaken Ariel with a kiss!
Locket: Oh really? I thought we had to stop them because they'll make Baked Alaska out of us if we don't!
When ponies try to say hello to the duchess in "The Prince and the Ponies":
Cherries Jubilee: Good evening, duchess!
The Duchess: WHO LET THOSE HORSES IN HERE?!
When Alonzo tries to kill Spike in "The Would Be Dragonslayer":
Alonzo: No one helps dragons!
Whizzer: Oh no! Well, you're absolutely wrong! We do! And this is how we do it! *knocks Alonzo off his camel*